Curable resin compositions

ABSTRACT

Some of the resin compositions are ultraviolet light or thermally curable, while others are ultraviolet light curable. One example of the ultraviolet light or thermally curable resin composition consists of a predetermined mass ratio of a (meth)acrylate cyclosiloxane monomer and a non-siloxane (meth)acrylate based monomer ranging from about &gt;0:&lt;100 to about 80:20; from 0 mass % to about 10 mass %, based on a total solids content of the resin composition, of an initiator selected from the group consisting of an azo-initiator, an acetophenone, a phosphine oxide, a brominated aromatic acrylate, and a dithiocarbamate; a surface additive; and a solvent.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 63/248,179, filed Sep. 24, 2021, the contents of which isincorporated by reference herein in its entirety.

REFERENCE TO SEQUENCE LISTING

The Sequence Listing submitted herewith is hereby incorporated byreference in its entirety. The name of the file isILI222B_IP-2196-US_Sequence_Listing_ST26.xml, the size of the file is10,092 bytes, and the date of creation of the file is Sep. 7, 2022.

BACKGROUND

Nanoimprinting technology enables the economic and effective productionof nanostructures. Nanoimprint lithography employs direct mechanicaldeformation of material by a stamp having nanostructures. The materialis cured while the stamp is in place to lock the shape of thenanostructures in the material.

Nanoimprint lithography has been used to manufacture patternedsubstrates, which may be used in a variety of applications. Somepatterned substrates include fluidic channels and discrete depressions.These patterned substrates may be built into flow cells. In some flowcells, active surface chemistry is introduced into the discretedepressions, while interstitial regions surrounding the discretedepressions remain inert. These flow cells may be particularly usefulfor detection and evaluation of a wide range of molecules (e.g., DNA),families of molecules, genetic expression levels, or single nucleotidepolymorphisms.

SUMMARY

Disclosed herein are several resin compositions, which are suitable foruse in nanoimprint lithography. The cured resins generated with examplesof the resin composition may exhibit no or low autofluorescence atfluorescent detection wavelengths of interest when exposed to violet orblue excitation wavelengths ranging from about 375 nm to about 500 nm.With no or low autofluorescence, the cured resins do not contribute, orcontribute minimally, to background fluorescence. A reduction in thebackground intensity increases the signal to noise ratio (SNR), whichenables signals at the fluorescent detection wavelengths to be readilyresolved. Thus, the cured resin compositions, and the resulting curedresins, may be particularly suitable for use in a variety offluorescent-based bioanalytical applications, such as DNA sequencing,detection of immobilized proteins, cells or enzyme-binding molecules,drug screening, toxicity testing, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

Features of examples of the present disclosure will become apparent byreference to the following detailed description and drawings, in whichlike reference numerals correspond to similar, though perhaps notidentical, components. For the sake of brevity, reference numerals orfeatures having a previously described function may or may not bedescribed in connection with other drawings in which they appear.

FIG. 1A through 1E are schematic perspective views which together depictan example of a method, where FIG. 1A illustrates a substrate, FIG. 1Billustrates nanoimprinting of a resin composition deposited on thesubstrate of FIG. 1A, FIG. 1C illustrates a cured, patterned resinformed from the nanoimprinting illustrated in FIG. 1B, FIG. 1Dillustrates a polymeric hydrogel deposited in depressions of the cured,patterned resin of FIG. 1C, and FIG. 1E illustrates primers grafted tothe polymeric hydrogel in the depressions of the cured, patterned resinof FIG. 1D;

FIG. 2 is a schematic, cross-sectional view taken along line 2-2 of theflow cell surface of FIG. 1E;

FIG. 3 is a graph depicting the autofluorescence data (in violet, blue,and green channels), in terms of FilterArea (integrated fluorescenceintensity (AU) using a selected collection band, Y axis) versusexcitation wavelength (nm, X axis), for a control example, a curedcomparative example resin, and two cured initiator free (meth)acrylatebased example resins;

FIG. 4 is a graph depicting the autofluorescence data (in violet, blue,and green channels), in terms of FilterArea (integrated fluorescenceintensity (AU) using a selected collection band, Y axis) versusexcitation wavelength (nm, X axis), for a control example, a curedcomparative example resin, and a cured (meth)acrylate based exampleresin containing an azo-initiator;

FIG. 5A and FIG. 5B are graphs depicting the Fourier-transform infraredspectroscopy (FTIR) intensity at 1636 cm⁻¹ (CH₂═CH—R stretching) (FIG.5A) and 1406 cm⁻¹ (C═C—H in-plane deformation) (FIG. 5B) for a controlexample, a cured initiator free (meth)acrylate based example resin, anda cured (meth)acrylate based example resin containing an azo-initiator;

FIG. 6 is a graph depicting the autofluorescence data (in the violetchannel), in terms of FilterArea (integrated fluorescence intensity (AU)using a selected collection band, Y axis) at the 405 nm excitationwavelength, for a control example, a cured comparative example resin,and cured (meth)acrylate based example resins containing differentinitiators;

FIG. 7 is a graph depicting the autofluorescence data (in violet, blue,and green channels), in terms of FilterArea (integrated fluorescenceintensity (AU) using a selected collection band, Y axis) versusexcitation wavelength (nm, X axis), for a control example, a curedcomparative example resin, and cured (meth)acrylate based example resinscontaining different (meth)acrylate monomers and the same initiator;

FIG. 8 is a graph depicting the cure time (seconds, Y axis) for a curedinitiator free (meth)acrylate based example resin, a cured(meth)acrylate based example resin containing an azo-initiator, andcured (meth)acrylate based example resin containing a phosphine oxideinitiator;

FIG. 9 is a graph depicting the autofluorescence data (in violet, blue,and green channels), in terms of FilterArea (integrated fluorescenceintensity (AU) using a selected collection band, Y axis) versusexcitation wavelength (nm, X axis), for a control example, a curedcomparative example resin, and cured epoxy based example resinscontaining different initiator combinations;

FIG. 10 is a graph depicting the cure time (seconds, Y axis) for some ofthe cured epoxy based example resins containing different initiatorcombinations; and

FIG. 11 is a graph depicting the corrected infrared (IR) intensity at2991 cm-1 (Y axis) for cured epoxy based example resins containingdifferent initiator combinations.

DETAILED DESCRIPTION

Some patterned biomedical systems, such as flow cells, include a curedresin composition that has discrete depressions (or wells) or trenchesformed therein. To form the depressions or trenches, the resincomposition (pre-curing) may be imprinted using a variety of techniques,such as nanoimprint lithography (NIL).

With nanoimprint lithography, the resin composition (includingpolymerizable multi-functional monomers) is deposited on a substrate.The deposited resin composition is patterned with an imprintingapparatus (e.g., a working stamp or template), which is pressed onto theresin surface. The resin composition deforms to fill the imprintingapparatus pattern. While the imprinting apparatus is still in contactwith the resin composition, polymerization of the resin composition isinitiated by exposure to light or heat, and the resin is cured. Afterthe resin composition is sufficiently crosslinked such that it is nolonger able to flow, the imprinting apparatus is peeled away from thesurface, leaving behind an imprinted resin surface. When nanoimprintingis successful, features of the imprinting apparatus are transferred tothe cured resin. The features (e.g., depressions or trenches) can thenbe functionalized with surface chemistry that enables fluorescent-basedsequencing, analyte detection, etc.

When the features have a low pitch (i.e., the spacing from the center ofone feature to the center of a directly adjacent feature(center-to-center spacing) or from the right edge or left edge of onefeature to, respectively, the right edge or left edge of a directlyadjacent feature (edge-to-edge spacing) is less than 500 nm), violet orblue imaging is used to achieve a desirable signal resolution. Asexamples, violet wavelength illumination may be particularly desirablefor features with a pitch ranging from about 250 nm to about 350 nm; andblue wavelength illumination may be particularly desirable for featureswith a pitch ranging from about 300 nm to about 500 nm. The wavelengthsof violet and blue light range from about 375 nm to 500 nm, which arevery close to the emission of many ultraviolet (UV) light sources (e.g.,365 nm). The emission spectra of molecules are mirror images of theirabsorption spectra, shifted to higher wavelengths typically by tens ofnanometers (Stokes-shift). Thus, many initiators that absorb at curingwavelengths (e.g., UV) and decompose to generate a reactive species,also generate by-products that emit when exposed to violet and/or bluelight. These by-products can cause the cured resins to exhibitundesirable levels of autofluorescence at excitation wavelengths ofinterest (e.g., violet excitation wavelengths ranging from about 375 nmto about 450 nm, or blue excitation wavelengths ranging from about 450nm to about 500 nm).

Fluorescence from the cured resin can increase the background noise, forexample, when imaging during a fluorescent-based bioanalyticalapplication (e.g., when imaging optical labels of nucleotides that havebeen incorporated into individual nascent strands formed in the featuresduring sequencing). Increased background noise can decrease signal tonoise ratios (SNRs) so that signals within individual features are moredifficult to be resolved.

Examples of the resin composition disclosed herein exhibit low or noautofluorescence when exposed to violet or blue excitation wavelengthsranging from about 375 nm to about 500 nm.

Some examples of the resin composition include a mixture of a(meth)acrylate cyclosiloxane monomer and a non-siloxane (meth)acrylatebased monomer without any photoinitiator. These examples polymerize uponexposure to light or heat without an initiator. Without the initiator,there are no initiator decomposition by-products that can lead toautofluorescence.

Other examples of the resin composition include a mixture of a(meth)acrylate cyclosiloxane monomer and a non-siloxane (meth)acrylatebased monomer with an azo-initiator, a acetophenone initiator, aphosphine oxide initiator, a brominated aromatic acrylate initiator, anda dithiocarbamate initiator. Each of these initiators has been found toboost the curing rate of these examples of the resin composition withoutalso increasing autofluorescence.

Still other examples of the resin composition include a mixture of twodifferent epoxy cyclosiloxane monomers (each having a 1:1 ratio of Si:Oin the cyclosiloxane), bis-(4-methylphenyl)iodonium hexafluorophosphateas a first initiator, and a second initiator selected from the groupconsisting of a free radical initiator and a cationic initiator otherthan bis-(4-methylphenyl)iodonium hexafluorophosphate. This combinationof initiators has also been found to boost the curing rate of theseexamples of the resin composition without also increasingautofluorescence.

As mentioned herein, the examples of the cured resin composition exhibitvery low or no autofluorescence when exposed to violet and blueexcitation wavelengths. As used herein, violet excitation wavelengthsinclude from about 375 nm to about 450 nm, and blue excitationwavelengths include from about 450 nm to about 500 nm. In anotherexample, the violet excitation wavelengths range from about 375 nm toabout 415 nm and the blue excitation wavelengths range from about 450 nmto about 465 nm. The examples of the cured resin composition may alsohave minimal violet and blue emissions. Also as used herein, violetemission wavelengths include from about 415 nm to about 455, and blueemission wavelengths include from about 480 nm to about 525 nm.

In some instances, the cured resin composition is described as having nofluorescence (emission of light) when exposed to violet excitationwavelengths and/or blue excitation wavelengths. No fluorescence or noautofluorescence means that the level of fluorescence is below athreshold limit of detection. In other instances, the cured resincomposition fluoresces (emits light) when exposed to violet excitationwavelengths and/or blue excitation wavelengths. In these instances, theterm “low autofluorescence” may mean that the emission level (of thecured resin when exposed to violet excitation wavelengths and/or blueexcitation wavelengths) is above the threshold limit of detection, butis low enough to be considered noise, and the noise does not interferewith the identification of signals of interest. In one example, theautofluorescence levels enable signal to noise ratios (SNRs) that arehigh enough so that signals from individual clusters can be resolvedduring sequencing.

It is to be understood that the definition of “low” or “low level”, interms of quantifying the autofluorescence (AF), may vary depending uponthe tool used to measure the autofluorescence and/or lamps used toprovide the excitation radiation. In the examples set forth herein, oneor more reference points are used to define the relative AF level. Asone example, the references are the AF level of 0.7 mm thick CORNING®EAGLE XG® glass (CEXG) and the AF level of an epoxy polyhedraloligomeric silsesquioxane resin, and a “low AF” can be defined relativeto the CEXG output and the epoxy resin output with violet or blue laserexcitation. The resin may have low AF if its autofluorescence is lessthan one half of the difference between the CEXG output and the epoxyresin output. The numerical values of the output (in arbitrary units) isrelevant in a relative sense, as it may depend on the material beingmeasured, the excitation and emission bands being measured, theintensity of exciting light, etc.

The examples of the resin composition disclosed herein also exhibit adesirable extent of cure (e.g., level of polymerization and/orcrosslinking) of the monomers or polymers in the resin composition whenexposed to relative short curing times (e.g., 60 seconds or less, suchas 30 seconds, 20 seconds, etc.). Resins that are under-cured are notfully vitrified and can exhibit reflow, which may manifest in a poor anduncontrolled depression shape in the patterned area. Additionally,under-cured resins may have low hardness values, which can increase thematerial's sensitivity to downstream processing. Fourier-transforminfrared spectroscopy (FTIR) intensity at 1636 cm⁻¹ (CH₂═CH—Rstretching) and 1406 cm⁻¹ (C═C—H in-plane deformation) may be used tomonitor the extent of cure for the (meth)acrylate resin compositionsdisclosed herein. Fourier-transform infrared spectroscopy (FTIR)intensity at 2991 cm⁻¹ may be used to monitor the extent of cure for theepoxy resin compositions disclosed herein. For example, the normalizedintensity at 2991 cm⁻¹ may be monitored with respect to a reference peakintensity at 2925 cm⁻¹. A higher extent of cure corresponds with a lowerintensity or corrected intensity at the given peaks.

Definitions

It is to be understood that terms used herein will take on theirordinary meaning in the relevant art unless specified otherwise. Inaddition to the terms “no autofluorescence” and “low autofluorescence”set forth above, several other terms are used herein. The meanings ofthese additional terms are set forth below.

The singular forms “a”, “an”, and “the” include plural referents unlessthe context clearly dictates otherwise.

The terms comprising, including, containing and various forms of theseterms are synonymous with each other and are meant to be equally broad.

The terms top, bottom, lower, upper, on, adjacent, etc. are used hereinto describe the flow cell and/or the various components of the flowcell. It is to be understood that these directional terms are not meantto imply a specific orientation, but are used to designate relativeorientation between components. The use of directional terms should notbe interpreted to limit the examples disclosed herein to any specificorientation(s).

The terms first, second, etc. also are not meant to imply a specificorientation or order, but rather are used to distinguish one componentfrom another.

It is to be understood that the ranges provided herein include thestated range and any value or sub-range within the stated range, as ifsuch values or sub-ranges were explicitly recited. For example, a rangeof about 400 nm to about 1 μm (1000 nm), should be interpreted toinclude not only the explicitly recited limits of about 400 nm to about1 μm, but also to include individual values, such as about 708 nm, about945.5 nm, etc., and sub-ranges, such as from about 425 nm to about 825nm, from about 550 nm to about 940 nm, etc. Furthermore, when “about”and/or “substantially” are/is utilized to describe a value, they aremeant to encompass minor variations (up to +/−10%) from the statedvalue.

An “acrylamide” is a functional group with the structure

where each H may alternatively be an alkyl, an alkylamino, analkylamido, an alkylthio, an aryl, a glycol, and optionally substitutedvariants thereof. Examples of monomers including an acrylamidefunctional group include azido acetamido pentyl acrylamide:

and N-isopropylacrylamide:

Other acrylamide monomers may be used, some examples of which are setforth herein.

As used herein the term “acrylate” refers to a “CH₂═CHCOO—” functionalgroup (i.e.,

Acrylates include substituted variations thereof (e.g., methacrylate isan example of an acrylate).

An “aldehyde,” as used herein, is an organic compound containing afunctional group with the structure —CHO, which includes a carbonylcenter (i.e., a carbon double-bonded to oxygen) with the carbon atomalso bonded to hydrogen and an R group, such as an alkyl or other sidechain. The general structure of an aldehyde is:

As used herein, “alkyl” refers to a straight or branched hydrocarbonchain that is fully saturated (i.e., contains no double or triplebonds). The alkyl group may have 1 to 20 carbon atoms. Example alkylgroups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl,tertiary butyl, pentyl, hexyl, and the like. As an example, thedesignation “C1-C4 alkyl” indicates that there are one to four carbonatoms in the alkyl chain, i.e., the alkyl chain is selected from thegroup consisting of methyl, ethyl, propyl, iso-propyl, n-butyl,isobutyl, sec-butyl, and t-butyl. An alkyl may be substituted orunsubstituted. An example of a substituted alkyl is a haloalkyl, or analkyl substituted with a halogen.

As used herein, “alkylamino” refers to an alkyl group in which one ormore of the hydrogen atoms are replaced by an amino group, where theamino group refers to an —NR_(a)R_(b) group, where R_(a) and R_(b) areeach independently selected from a C1-C6 alkyl, C2-C6 alkenyl, C2-C6alkynyl, C3-C7 carbocycle, C6-C10 aryl, a 5-10 membered heteroaryl, anda 5-10 membered heterocycle.

As used herein, “alkylamido” refers to an alkyl group in which one ormore of the hydrogen atoms are replaced by a C-amido group or an N-amidogroup. A “C-amido” group refers to a “—C(═O)N(R_(a)R_(b))” group inwhich R_(a) and R_(b) can independently be selected from the groupconsisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, aryl, heteroaryl, heteroalicycle, aralkyl, or(heteroalicyclic)alkyl. An “N-amido” group refers to a “RC(═O)N(R_(a))—”group in which R and R_(a) can independently be selected from the groupconsisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkynyl, aryl, heteroaryl, heteroalicycle, aralkyl, or(heteroalicyclic)alkyl. Any alkylamido may be substituted orunsubstituted.

As used herein, “alkylthio” refers to RS—, in which R is an alkyl. Thealkylthio can be substituted or unsubstituted.

As used herein, “alkene” or “alkenyl” refers to a straight or branchedhydrocarbon chain containing one or more double bonds. The alkenyl groupmay have 2 to 20 carbon atoms. Example alkenyl groups include ethenyl,propenyl, butenyl, pentenyl, hexenyl, and the like.

As used herein, “alkyne” or “alkynyl” refers to a straight or branchedhydrocarbon chain containing one or more triple bonds. The alkynyl groupmay have 2 to 20 carbon atoms.

An “amine” or “amino” functional group refers to an —NR_(a)R_(b) group,where R_(a) and R_(b) are each independently selected from hydrogen(e.g.,

C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C7 carbocycle, C6-C10aryl, 5-10 membered heteroaryl, and 5-10 membered heterocycle, asdefined herein.

As used herein, “aralkyl” and “aryl(alkyl)” refer to an aryl groupconnected, as a substituent, via a lower alkylene group. The loweralkylene and aryl group of an aralkyl may be substituted orunsubstituted. Examples include but are not limited to benzyl,2-phenylalkyl, 3-phenylalkyl, and naphthylalkyl.

The term “aryl” refers to an aromatic ring or ring system (i.e., two ormore fused rings that share two adjacent carbon atoms) containing onlycarbon in the ring backbone. When the aryl is a ring system, every ringin the system is aromatic. The aryl group may have 6 to 18 carbon atoms.Examples of aryl groups include phenyl, naphthyl, azulenyl, andanthracenyl. Any aryl may be a heteroaryl, with at least one heteroatom,that is, an element other than carbon (e.g., nitrogen, oxygen, sulfur,etc.), in ring backbone.

As used herein, the term “attached” refers to the state of two thingsbeing joined, fastened, adhered, connected or bound to each other,either directly or indirectly. For example, a nucleic acid can beattached to a polymer hydrogel by a covalent or non-covalent bond. Acovalent bond is characterized by the sharing of pairs of electronsbetween atoms. A non-covalent bond is a physical bond that does notinvolve the sharing of pairs of electrons and can include, for example,hydrogen bonds, ionic bonds, van der Waals forces, hydrophilicinteractions and hydrophobic interactions.

An “azide” or “azido” functional group refers to —N₃.

As used herein, “carbocycle” means a non-aromatic cyclic ring or ringsystem containing only carbon atoms in the ring system backbone. Whenthe carbocycle is a ring system, two or more rings may be joinedtogether in a fused, bridged or spiro-connected fashion. Carbocycles mayhave any degree of saturation, provided that at least one ring in a ringsystem is not aromatic. Thus, carbocycles include cycloalkyls,cycloalkenyls, and cycloalkynyls. The carbocycle group may have 3 to 20carbon atoms. Examples of carbocycle rings include cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cyclohexenyl, 2,3-dihydro-indene,bicyclo[2.2.2]octanyl, adamantyl, and spiro[4.4]nonanyl. Any of thecarbocycles may be heterocycles, with at least one heteroatom in ringbackbone.

As used herein, “cycloalkyl” refers to a completely saturated (no doubleor triple bonds) mono- or multi-cyclic hydrocarbon ring system. Whencomposed of two or more rings, the rings may be joined together in afused fashion. Cycloalkyl groups can contain 3 to 10 atoms in thering(s). In some examples, cycloalkyl groups can contain 3 to 8 atoms inthe ring(s). A cycloalkyl group may be unsubstituted or substituted.Example cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, and cyclooctyl.

As used herein, “cycloalkenyl” or “cycloalkene” means a carbocycle ringor ring system having at least one double bond, wherein no ring in thering system is aromatic. Examples include cyclohexenyl or cyclohexeneand norbornenyl or norbornene.

As used herein, “cycloalkynyl” or “cycloalkyne” means a carbocycle ringor ring system having at least one triple bond, wherein no ring in thering system is aromatic. An example is cyclooctyne. Another example isbicyclononyne. Still another example is dibenzocyclooctyne (DBCO).

The term “depositing,” as used herein, refers to any suitableapplication technique, which may be manual or automated, and, in someinstances, results in modification of the surface properties. Depositingmay be performed using vapor deposition techniques, coating techniques,grafting techniques, or the like. Some specific examples includechemical vapor deposition (CVD), spray coating (e.g., ultrasonic spraycoating), spin coating, dunk or dip coating, doctor blade coating,puddle dispensing, flow through coating, aerosol printing, screenprinting, microcontact printing, inkjet printing, or the like.

As used herein, the term “depression” refers to a discrete concavefeature in a patterned resin having a surface opening that is at leastpartially surrounded by interstitial region(s) of the cured resin.Depressions can have any of a variety of shapes at their opening in asurface including, as examples, round, elliptical, square, polygonal,star shaped (with any number of vertices), etc. The cross-section of adepression taken orthogonally with the surface can be curved, square,polygonal, hyperbolic, conical, angular, etc. The depression may alsohave more complex architectures, such as ridges, step features, etc.Depressions are one example of the features that can be formed usingnanoimprint lithography. Another example of such a feature is atrench/trough.

The term “each,” when used in reference to a collection of items, isintended to identify an individual item in the collection, but does notnecessarily refer to every item in the collection. Exceptions can occurif explicit disclosure or context clearly dictates otherwise.

The term “epoxy” as used herein refers to

The term “epoxy cyclosiloxane monomer having a 1:1 ratio of Si:O in thecyclosiloxane” refers to 3 or more repeating units of silicon and oxygenin a closed loop or ring, where the ring is functionalized with anepoxy-containing functional group.

“FilterArea” is the integrated fluorescence intensity (AU) using aselected collection band (collection filter), whereby the wavelengthsare chosen to match the sequencing imaging wavelengths (Violet: 418-550nm, Blue: 482-525 nm, Green: 575-625 nm).

As used herein, the term “flow cell” is intended to mean a vessel havinga flow channel where a reaction can be carried out, an inlet fordelivering reagent(s) to the flow channel, and an outlet for removingreagent(s) from the flow channel. In some examples, the flow cellenables the detection of the reaction that occurs in the flow channel.For example, the flow cell may include one or more transparent surfacesallowing for the optical detection of arrays, optically labeledmolecules, or the like within the flow channel.

As used herein, a “flow channel” or “channel” may be an area definedbetween two bonded components, which can selectively receive a liquidsample. In examples disclosed herein, the flow channel may be definedbetween a patterned substrate and a lid, and thus may be in fluidcommunication with one or more depressions defined in the patternedsubstrate or resin. The flow channel may also be defined between twopatterned substrate surfaces that are bonded together.

As used herein, “heteroalicyclic” or “heteroalicycle” refers to three-,four-, five-, six-, seven-, eight-, nine-, ten-, up to 18-memberedmonocyclic, bicyclic, and tricyclic ring system wherein carbon atomstogether with from 1 to 5 heteroatoms constitute said ring system. Aheteroalicyclic ring system may optionally contain one or moreunsaturated bonds situated in such a way, however, that a fullydelocalized pi-electron system does not occur throughout all the rings.The heteroatoms are independently selected from oxygen, sulfur, andnitrogen. A heteroalicyclic ring system may further contain one or morecarbonyl or thiocarbonyl functionalities, so as to make the definitioninclude oxo-systems and thio-systems such as lactams, lactones, cyclicimides, cyclic thioimides, and cyclic carbamates. The rings may bejoined together in a fused fashion. Additionally, any nitrogens in aheteroalicyclic may be quaternized. Heteroalicycle or heteroalicyclicgroups may be unsubstituted or substituted. Examples of such“heteroalicyclic” or “heteroalicycle” groups include 1,3-dioxin,1,3-dioxane, 1,4-dioxane, 1,2-dioxolane, 1,3-dioxolane, 1,4-dioxolane,1,3-oxathiane, 1,4-oxathiin, 1,3-oxathiolane, 1,3-dithiole,1,3-dithiolane, 1,4-oxathiane, tetrahydro-1,4-thiazine, 2H-1,2-oxazine,maleimide, succinimide, barbituric acid, thiobarbituric acid,dioxopiperazine, hydantoin, dihydrouracil, trioxane,hexahydro-1,3,5-triazine, imidazoline, imidazolidine, isoxazoline,isoxazolidine, oxazoline, oxazolidine, oxazolidinone, thiazoline,thiazolidine, morpholine, oxirane, piperidine N-oxide, piperidine,piperazine, pyrrolidine, pyrrolidone, pyrrolidione, 4-piperidone,pyrazoline, pyrazolidine, 2-oxopyrrolidine, tetrahydropyran, 4H-pyran,tetrahydrothiopyran, thiamorpholine, thiamorpholine sulfoxide,thiamorpholine sulfone, and their benzo-fused analogs (e.g.,benzimidazolidinone, tetrahydroquinoline, 3,4-methylenedioxyphenyl).

A “(heteroalicyclic)alkyl” refers to a heterocyclic or a heteroalicyclicgroup connected, as a substituent, via a lower alkylene group. The loweralkylene and heterocycle or a heterocycle of a (heteroalicyclic)alkylmay be substituted or unsubstituted. Examples include but are notlimited tetrahydro-2H-pyran-4-yl)methyl, (piperidin-4-yl)ethyl,(piperidin-4-yl)propyl, (tetrahydro-2H-thiopyran-4-yl)methyl, and(1,3-thiazinan-4-yl)methyl.

As used herein, “heteroaryl” refers to an aromatic ring or ring system(i.e., two or more fused rings that share two adjacent atoms) thatcontain(s) one or more heteroatoms, that is, an element other thancarbon, including but not limited to, nitrogen (N), oxygen (O) andsulfur (S), in the ring backbone. When the heteroaryl is a ring system,every ring in the system is aromatic. The heteroaryl group may have 5-18ring members.

As used herein, “heterocycle” means a non-aromatic cyclic ring or ringsystem containing at least one heteroatom in the ring backbone.Heterocycles may be joined together in a fused, bridged orspiro-connected fashion. Heterocycles may have any degree of saturationprovided that at least one ring in the ring system is not aromatic. Inthe ring system, the heteroatom(s) may be present in either anon-aromatic or aromatic ring. The heterocycle group may have 3 to 20ring members (i.e., the number of atoms making up the ring backbone,including carbon atoms and heteroatoms). In some examples, theheteroatom(s) are O, N, or S.

The term “hydrazine” or “hydrazinyl” as used herein refers to a —NHNH₂group.

As used herein, the term “hydrazone” or “hydrazonyl” as used hereinrefers to a

group in which R_(a) and R_(b) are each independently selected fromhydrogen, C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C3-7 carbocyclyl,C6-10 aryl, 5-10 membered heteroaryl, and 5-10 membered heterocyclyl, asdefined herein.

As used herein, “hydroxy” or “hydroxyl” refers to an —OH group.

As used herein, an “initiator” is a molecule that undergoes a reactionupon absorption of radiation or heat or upon exposure to free radicals,thereby producing a reactive species. Initiators are capable ofinitiating or catalyzing chemical reactions that result in changes inthe solubility and/or physical properties of formulations. A “cationicinitiator” or “photoacid generator” (PAG) is a molecule that becomesacidic upon exposure to radiation or to free radicals. PAGs generallyundergo proton photodissociation irreversibly. A “free radicalinitiator” is a molecule that generates a radical species upon exposureto radiation or heat and that promotes radical reactions.

As used herein, the term “interstitial region” refers to an area on asurface (e.g., of a cured patterned resin) that separates depressions orother features. For example, an interstitial region can separate onefeature of an array from another feature of the array. The two featuresthat are separated from each other can be discrete, i.e., lackingphysical contact with each other. In another example, an interstitialregion can separate a first portion of a feature from a second portionof a feature. In many examples, the interstitial region is continuouswhereas the features are discrete, for example, as is the case for aplurality of depressions defined in an otherwise continuous surface. Inother examples, the interstitial regions and the features are discrete,for example, as is the case for a plurality of trenches separated byrespective interstitial regions. The separation provided by aninterstitial region can be partial or full separation. Interstitialregions may have a surface material that differs from the surfacematerial of the features. For example, features of an array can have anamount or concentration of a polymeric hydrogel and primer(s) thatexceeds the amount or concentration present at the interstitial regions.In some examples, the polymeric hydrogel and primer(s) may be present indepressions or trenches and may not be present at the interstitialregions.

The term “(meth)” indicates that the acrylate, etc., may or may notinclude the methyl group.

A “(meth)acrylate cyclosiloxane monomer” includes 3 or more repeatingunits of silicon and oxygen in a closed loop or ring, where the ring isfunctionalized with a (meth)acrylate-containing functional group.

“Nitrile oxide,” as used herein, means a “R_(a)C≡N⁺O⁻” group in whichR_(a) is defined herein. Examples of preparing nitrile oxide include insitu generation from aldoximes by treatment with chloramide-T or throughaction of base on imidoyl chlorides [RC(Cl)═NOH] or from the reactionbetween hydroxylamine and an aldehyde.

“Nitrone,” as used herein, means a

group in which R₁, R₂, and R₃ may be any of the R_(a) and R_(b) groupsdefined herein.

A “non-siloxane (meth)acrylate based monomer” is a polymerizableacrylate or methacrylate that does not include any repeating units ofsilicon and oxygen.

As used herein, a “nucleotide” includes a nitrogen containingheterocyclic base, a sugar, and one or more phosphate groups.Nucleotides are monomeric units of a nucleic acid sequence. In RNA(ribonucleic acid), the sugar is a ribose, and in DNA (deoxyribonucleicacid), the sugar is a deoxyribose, i.e. a sugar lacking a hydroxyl groupthat is present at the 2′ position in ribose. The nitrogen containingheterocyclic base (i.e., nucleobase) can be a purine base or apyrimidine base. Purine bases include adenine (A) and guanine (G), andmodified derivatives or analogs thereof. Pyrimidine bases includecytosine (C), thymine (T), and uracil (U), and modified derivatives oranalogs thereof. The C-1 atom of deoxyribose is bonded to N-1 of apyrimidine or N-9 of a purine. A nucleic acid analog may have any of thephosphate backbone, the sugar, or the nucleobase altered. Examples ofnucleic acid analogs include, for example, universal bases orphosphate-sugar backbone analogs, such as peptide nucleic acid (PNA).

As used herein, the “primer” is defined as a single stranded nucleicacid sequence (e.g., single strand DNA). Some primers, which may bereferred to as amplification primers, serve as a starting point fortemplate amplification and cluster generation. Other primers, which maybe referred to as sequencing primers, serve as a starting point for DNAsynthesis. The 5′ terminus of the primer may be modified to allow acoupling reaction with a functional group of the polymeric hydrogel. Theprimer length can be any number of bases long and can include a varietyof non-natural nucleotides. In an example, the sequencing primer is ashort strand, ranging from 10 to 60 bases, or from 20 to 40 bases.

The term “resin composition” refers to any of the monomer mixtures setforth herein. The resin composition may also include one or moreinitiators as defined herein, a surface additive, and a solvent.

A “spacer layer,” as used herein refers to a material that bonds twocomponents together. In some examples, the spacer layer can be aradiation-absorbing material that aids in bonding, or can be put intocontact with a radiation-absorbing material that aids in bonding. Thespacer layer may be present in a bonding region, e.g., an area on asubstrate that is to be bonded to another material, which may be, asexamples, a spacer layer, a lid, another substrate, etc., orcombinations thereof (e.g., the spacer layer and a lid). The bond thatis formed at the bonding region may be a chemical bond (as describedabove), or a mechanical bond (e.g., using a fastener, etc.).

A “thiol” functional group refers to —SH.

As used herein, the terms “tetrazine” and “tetrazinyl” refer tosix-membered heteroaryl group comprising four nitrogen atoms. Tetrazinecan be optionally substituted.

“Tetrazole,” as used herein, refers to a five-membered heterocyclicgroup including four nitrogen atoms. Tetrazole can be optionallysubstituted.

The term “thermally curable” means that polymerization or polymerizationand crosslinking of the resin composition is/are initiated by exposureto heat. The temperature for thermal curing will depend upon themonomers in the resin composition.

The term “ultraviolet light curable” means polymerization orpolymerization and crosslinking of the resin composition is/areinitiated by exposure to ultraviolet light, i.e., radiation withwavelengths ranging from about 280 nm to about 400 nm).

(Meth)Acrylate-Based Resin Compositions

Some of the examples disclosed herein are ultraviolet light and/orthermally curable (meth)acrylate-based resin compositions. In someexamples, the ultraviolet light or thermally curable resin compositioncomprises or consists of a predetermined mass ratio of a (meth)acrylatecyclosiloxane monomer and a non-siloxane (meth)acrylate based monomerranging from about >0:<100 to about 80:20; from 0 mass % to about 10mass %, based on a total solids content of the resin composition, of aninitiator (e.g., a free radical initiator) selected from the groupconsisting of an azo-initiator, an acetophenone, a phosphine oxide, abrominated aromatic acrylate, and a dithiocarbamate; a surface additive;and a solvent. When the resin composition consists of the listedcomponents, it is to be understood that it does not include any othercomponents.

In any of the (meth)acrylate-based resin compositions, the(meth)acrylate cyclosiloxane monomer is2,4,6,8-tetramethyl-2,4,6,8-tetrakis[3-acryloyloxypropyl]cyclotetrasiloxane:

and the non-siloxane (meth)acrylate based monomer is selected from thegroup consisting of glycerol dimethacrylate, mixture of isomers:

where R is H or

glycerol 1,3-diglycerolate diacrylate

pentaerythritol triacrylate:

pentaerythritol tetraacrylate:

bisphenol A glycerolate diacrylate:

trimethylpropane triacrylate:

3-(acryloyloxy)-2-hydroxypropyl methacrylate:

poly(ethylene glycol) dimethacrylate:

ethylene glycol dimethacrylate:

and combinations thereof.

In any of the (meth)acrylate-based resin compositions, the predeterminedmass ratio of the (meth)acrylate cyclosiloxane monomer and thenon-siloxane (meth)acrylate based monomer ranges from about greater than(>) 0: less than (<)100 to about 80:20 (4:1). In one example, the massratio of the (meth)acrylate cyclosiloxane monomer and the non-siloxane(meth)acrylate based monomer is 50:50 (1:1).

In any of the (meth)acrylate-based resin compositions, the total amountof the combination of (meth)acrylate monomers ranges from about 87 mass% to less than 100 mass %, based on the total solids in the resincomposition. The total amount of the (meth)acrylate monomers dependsupon the other solids, e.g., the surface additive and the initiator (ifincluded), that are present in the resin composition. In one example,the (meth)acrylate monomers make up from about 93 mass % to about 98.5mass % of the total solids in the resin composition.

The surface additive can adjust the surface tension of the(meth)acrylate-based resin compositions, which can improve thedetachability of the resin from an imprinting apparatus (e.g., a workingstamp), improve the coatability of the resin composition, promote thinfilm stability, and/or improve leveling. Examples of surface additivesinclude polyacrylate polymers (such as BYK®-350 available from BYK). Theamount of the surface additive may be 3 mass % or less, based on thetotal mass of the (meth)acrylate-based resin compositions.

Any example of the (meth)acrylate-based resin composition may alsoinclude a solvent. The solvent may be added to achieve a desiredviscosity for the deposition technique being used to apply the resincomposition. Examples of the resin composition viscosity (e.g., afterthe solvent is introduced) range from about 1.75 mPa to about 2.2 mPa(measured at 25° C.). The viscosity may be higher or lower if desired.Examples of suitable solvents include propylene glycol monomethyl etheracetate (PGMEA), toluene, dimethyl sulfoxide (DMSO), tetrahydrofuran(THF), etc. In some examples, the solvent is PGMEA. The total solidsconcentration of the (meth)acrylate-based resin composition may rangefrom about 15 mass % to about 60 mass % (based on the total mass of theresin composition), and the amount of solvent may range from about 40mass % to about 85 mass % (based on the mass of the resin composition).The upper limits of the total solids may be higher depending upon therespective solubility of the solid component(s) in the solvent that isselected.

The (meth)acrylate cyclosiloxane monomer and the non-siloxane(meth)acrylate based monomer polymerize upon exposure to UV light orheat without an initiator, and thus one example of the(meth)acrylate-based resin composition does not include an initiator. Inthis example, the ultraviolet light or thermally curable resincomposition consists of the predetermined mass ratio of the(meth)acrylate cyclosiloxane monomer and a non-siloxane (meth)acrylatebased monomer ranging from about >0:<100 to about 80:20; the surfaceadditive; and the solvent. Any example and amounts of the surfaceadditive and the solvent may be used in the initiator free example ofthe (meth)acrylate-based resin composition.

As mentioned, any example of the (meth)acrylate-based resin compositionthat is free of the initiator is ultraviolet light curable or thermallycurable. In one example, a 365 nm UV light source may be used to curethis example of the resin composition. In another example, a broadspectrum light source (e.g., from about 270 nm to about 600 nm) may beused. In another example, heat ranging from about 130° C. to about 140°C. may be used to cure this example of the resin composition.

While the (meth)acrylate cyclosiloxane monomer and the non-siloxane(meth)acrylate based monomer polymerize upon exposure to UV light orheat without an initiator, one example of the (meth)acrylate-based resincomposition includes an azo-initiator to reduce the cure time andenhance the extent of cure. The azo-initiators disclosed herein arethermal initiators. However, when exposed to light (e.g., from 340 nm to380 nm UV light), the azo-initiators disclosed herein also decompose togenerate free radicals, which can initiate polymerization of monomerscontaining (meth)acrylate chemistries. Thus, the azo-initiatorsdisclosed herein can be used as photoinitiators. The generated radicalsor by-products of the azo-initiator reactions have little or noautofluorescence when exposed to visible light (including violet andblue excitation wavelengths). Thus, the addition of the azo-initiatordoes not deleteriously increase the autofluorescence of the cured resin.As such, in one example, the resin composition includes the initiator;the initiator is the azo-initiator; and the azo-initiator is selectedfrom the group consisting of azobisisobutyronitrile:

2,2′-azobis(2,4-dimethylvaleronitrile):

1,1′-azobis(cyclohexanecarbonitrile):

2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile):

dimethyl 2,2′-azobis(2-methylpropionate):

and 2,2′-Azobis(N-butyl-2-methylpropionamide:

When the azo-initiator is used, it may be present in an amount rangingfrom greater than 0 mass % to about 6 mass %, based on the total solidsof the resin composition. In one example, the azo-initiator is presentin an amount ranging from about 2 mass % to about 5 mass %, based on thetotal solids of the resin composition.

The azo-initiator has been found to be successful in enhancing thecuring rate and extent of cure without an additional photosensitizer.Thus, in one example, the (meth)acrylate-based, ultraviolet light orthermally curable resin composition comprises the predetermined massratio of the (meth)acrylate cyclosiloxane monomer and the non-siloxane(meth)acrylate based monomer ranging from about >0:<100 to about 80:20;from greater than 0 mass % to about 5 mass %, based on a total solidscontent of the resin composition, of the azo-initiator; the surfaceadditive; and the solvent, wherein the resin composition is free of aphotosensitizer. In this example, the azo-initiator is also selectedfrom the group consisting of azobisisobutyronitrile;2,2′-azobis(2,4-dimethylvaleronitrile);1,1′-azobis(cyclohexanecarbonitrile);2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile); dimethyl2,2′-azobis(2-methylpropionate); and2,2′-Azobis(N-butyl-2-methylpropionamide.

Any example of the (meth)acrylate-based resin composition that includesthe azo-initiator also includes the surface additive and the solvent.Any example and amounts of the surface additive and the solvent may beused.

Any example of the (meth)acrylate-based resin composition that includesthe azo-initiator is ultraviolet light curable or thermally curable. Inone example, a 365 nm UV light source may be used to cure this exampleof the resin composition. In another example, a broad spectrum lightsource (e.g., from about 270 nm to about 600 nm) may be used. In anotherexample, heat ranging from about 30° C. to about 140° C. may be used tocure this example of the resin composition.

While the (meth)acrylate cyclosiloxane monomer and the non-siloxane(meth)acrylate based monomer polymerize upon exposure to UV lightwithout an initiator, examples of the (meth)acrylate-based resincomposition may include an acetophenone initiator, a phosphine oxideinitiator, a brominated aromatic acrylate initiator, and adithiocarbamate initiator to significantly reduce the UV cure time andenhance the extent of UV cure. When exposed to UV light, theacetophenone initiator, the phosphine oxide initiator, the brominatedaromatic acrylate initiator, and the dithiocarbamate initiator eachdecompose to generate free radicals (e.g., via α-cleavage), which caninitiate polymerization of monomers containing (meth)acrylatechemistries. Thus, the acetophenone initiator, the phosphine oxideinitiator, the brominated aromatic acrylate initiator, or thedithiocarbamate initiator can be used as photoinitiators. In someinstances, the rapid curing rate of each of these initiators enablesvery few, if any, by-products to form. As such, very few, if any,components that can increase autofluorescence are introduced into thecured resin. In other instances, decomposition products/by-products thathave low autofluorescence are formed. Thus, the addition of theacetophenone initiator, the phosphine oxide initiator, the brominatedaromatic acrylate initiator, or the dithiocarbamate initiator does notdeleteriously increase the autofluorescence of the cured resin.

In one example, the (meth)acrylate-based resin composition includes theinitiator; the initiator is the acetophenone; and the acetophenone isselected from the group consisting of2,2-dimethoxy-2-phenylacetophenone:

and 2-hydroxy-2-methylpriophenone:

In another example, the (meth)acrylate-based resin composition includesthe initiator; the initiator is the phosphine oxide; and the phosphineoxide is selected from the group consisting ofdiphenyl(2,4,6-trimethylbenzoyl)phosphine oxide:

phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide:

diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide:

ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate:

and combinations thereof.

In still another example, the (meth)acrylate-based resin compositionincludes the initiator; the initiator is the brominated aromaticacrylate; and the brominated aromatic acrylate is pentabromobenzylacrylate:

In yet a further example, the (meth)acrylate-based resin compositionincludes the initiator; the initiator is the dithiocarbamate; and thedithiocarbamate is benzyl diethyldithiocarbamate:

Thus, an example of the (meth)acrylate based, ultraviolet light curableresin composition comprises the predetermined mass ratio of the(meth)acrylate cyclosiloxane monomer and a non-siloxane (meth)acrylatebased monomer ranging from about >0:<100 to about 80:20; the initiatorselected from the group consisting of the acetophenone, the phosphineoxide, the brominated aromatic acrylate, and the dithiocarbamate; thesurface additive; and the solvent. Any example and amounts of thesurface additive and the solvent set forth herein may be used in thisexample.

When the acetophenone initiator, the phosphine oxide initiator, thebrominated aromatic acrylate initiator, or the dithiocarbamate initiatoris used, the respective initiator may be present in an amount rangingfrom greater than 0 mass % to about 10 mass %, based on the total solidsof the resin composition. In one example, the acetophenone initiator,the phosphine oxide initiator, the brominated aromatic acrylateinitiator, or the dithiocarbamate initiator is present in an amountranging from about 2 mass % to about 8 mass %, based on the total solidsof the resin composition.

Any example of the (meth)acrylate-based resin composition that includesthe acetophenone initiator, the phosphine oxide initiator, thebrominated aromatic acrylate initiator, or the dithiocarbamate initiatoris ultraviolet light curable. In one example, a 365 nm UV light sourcemay be used to cure this example of the resin composition. In anotherexample, a broad spectrum light source (e.g., from about 270 nm to about600 nm) may be used.

An example of a method for making any example of the(meth)acrylate-based resin compositions disclosed herein includes mixingthe (meth)acrylate cyclosiloxane monomer and the non-siloxane(meth)acrylate based monomer at the mass ratio ranging fromabout >0:<100 to about 80:20, adding the surface additive to themixture, and diluting the mixture with the solvent. Some examplesfurther include mixing in any one of: the azo-initiator, theacetophenone initiator, the phosphine oxide initiator, the brominatedaromatic acrylate initiator, or the dithiocarbamate initiator at thedesired mass %.

Epoxy-Based Resin Compositions

Some of the examples disclosed herein are ultraviolet light curableepoxy-based resin compositions. In some examples, the ultraviolet lightcurable resin composition comprises or consists of a predetermined massratio of a first epoxy cyclosiloxane monomer having a 1:1 ratio of Si:Oin the cyclosiloxane and a second epoxy cyclosiloxane monomer having a1:1 ratio of Si:O in the cyclosiloxane, wherein the first and secondepoxy cyclosiloxane monomers are different, and wherein thepredetermined mass ratio ranges from about 3:7 to about 7:3;bis-(4-methylphenyl)iodonium hexafluorophosphate as a first initiator; asecond initiator selected from the group consisting of a free radicalinitiator and a cationic initiator other thanbis-(4-methylphenyl)iodonium hexafluorophosphate; a surface additive;and a solvent. When the resin composition consists of the listedcomponents, it is to be understood that it does not include any othercomponents.

In any of the epoxy-based resin compositions, two different epoxycyclosiloxane monomers are used, where the ratio of silicon atoms tooxygen atoms in the rings of each monomer is 1:1. In an example, thefirst epoxy cyclosiloxane monomer is epoxycyclohexyltetramethylcyclotetrasiloxane:

and the second epoxy cyclosiloxane monomer is glycidylcyclotetrasiloxane:

where R is:

In any of the epoxy-based resin compositions, the predetermined massratio of the first epoxy cyclosiloxane monomer to the second epoxycyclosiloxane monomer ranges from 3:7 to about 7:3. In one example, themass ratio of the first epoxy cyclosiloxane monomer and the second epoxycyclosiloxne monomer is 1.5:1.

In any of the epoxy-based resin compositions, the total amount of thecombination of epoxy monomers ranges from about 61 mass % to less than100 mass %, based on the total solids in the resin composition. Thetotal amount of the epoxy monomers depends upon the other solids, e.g.,the surface additive and the initiator (if included), that are presentin the resin composition. In one example, the epoxy monomers make upfrom about 67 mass % to about 90 mass % of the total solids in the resincomposition.

Similar to the (meth)acrylate-based resin compositions, the surfaceadditive can be added to the epoxy-based resin compositions to adjustthe surface tension. As noted herein, adjusting the surface tension canimprove the detachability of the resin from an imprinting apparatus(e.g., a working stamp), improve the coatability of the resincomposition, promote thin film stability, and/or improve leveling. Anyexample of the surface additive set forth for the (meth)acrylate-basedresin compositions may be used in the epoxy-based resin compositions.The amount of the surface additive may be 3 mass % or less, based on thetotal mass of the epoxy-based resin compositions.

Any example of the epoxy-based resin composition may also include asolvent. Similar to the (meth)acrylate-based resin compositions, thesolvent may be added to the epoxy-based resin composition to achieve adesired viscosity for the deposition technique being used to apply theresin composition. Examples of the resin composition viscosity (e.g.,after the solvent is introduced) ranges from about 1.75 mPa to about 2.2mPa (measured at 25° C.). The viscosity may also be higher or lower. Anyexample of the solvent set forth herein for the (meth)acrylate-basedresin compositions may be used in the epoxy-based resin compositions.The total solids concentration of the epoxy-based resin composition mayrange from about 15 mass % to about 60 mass % (based on the total massof the resin composition), and the amount of solvent may range fromabout 40 mass % to about 85 mass % (based on the mass of the resincomposition). The upper limits of the total solids may be higherdepending upon the respective solubility of the solid component(s) inthe solvent that is selected. In some examples, the solid content isabout 30% or less.

The epoxy-based resin compositions include a specific photoinitiatorpackage, which includes bis-(4-methylphenyl)iodonium hexafluorophosphateas a first (cationic) initiator and a second initiator, where the secondinitiator is either a free radical initiator or a cationic initiatorother than bis-(4-methylphenyl)iodonium hexafluorophosphate.

When the combination of bis-(4-methylphenyl)iodonium hexafluorophosphateand a free radical initiator are used, the free radicals generated bythe free radical initiator react with the bis-(4-methylphenyl)iodoniumhexafluorophosphate (which is a cationic initiator/photoacid generator),which decomposes to generate a superacid, which, in turn, initiates thepolymerization and crosslinking of the epoxy monomers. It is believedthat the bis-(4-methylphenyl)iodonium hexafluorophosphate and theselected free radical initiator do not undergo intramolecularinteractions that lead to undesirable autofluorescence in violet and/orblue excitation wavelengths of interest.

When the second initiator is the free radical initiator, the freeradical initiator is selected from the group consisting of1,1,2,2-tetraphenyl-1,2-ethanediol:

ethyl pyruvate:

4-cyano-4-(phenylcarbonothioylthio)pentanoic acid:

and ethyl-3-methyl-2-oxobutanoate:

When the combination of bis-(4-methylphenyl)iodonium hexafluorophosphateand another cationic initiator are used, the combination of photoacidgenerators have a surprising synergistic effect that significantly anddesirably alters the extent of cure, e.g., reduces corrected intensityat 2991 cm⁻¹ in a relatively short time period. It is believed thateither or both of the cationic initiators behave as both superacidgenerators and as radical initiators.

When the second initiator is the cationic initiator, the cationicinitiator is selected from the group consisting ofbis[4-(tert-butyl)phenyl]iodoniumtetra(nonafluoro-tert-butoxy)aluminate:

and tris(4-((4-acetylphenyl)thio)phenyl)-sulfoniumtetrakis(perfluoro-phenyl)borate (PAG 290):

where R is

In an example of the epoxy-based resin composition, thebis-(4-methylphenyl)iodonium hexafluorophosphate is present in an amountranging from about 3 mass % to about 10 mass %, based on a total solidscontent of the resin composition; and the second initiator is present inan amount ranging from about 1 mass % to about 26 mass %, based on thetotal solids content of the resin composition. In one example, thebis-(4-methylphenyl)iodonium hexafluorophosphate is present in an amountranging from about 4 mass % to about 5 mass % and the second initiatoris present in an amount ranging from about 2 mass % to about 26 mass %.

As mentioned, any example of the epoxy-based resins are ultravioletlight curable. In one example, a 365 nm UV light source may be used tocure this example of the resin composition.

An example of a method for making any example of the epoxy-based resincompositions disclosed herein includes mixing the first epoxycyclosiloxane monomer and the second epoxy cyclosiloxane monomer at themass ratio ranging from 3:7 to about 7:3, adding the initiators and thesurface additive to the mixture, and dissolving the mixture with thesolvent.

Flow Cells and Method

Any example of the resin composition disclosed herein may be used in theformation of the flow cell. The resin compositions may be patternedusing nanoimprint lithography to generate the features of the flow cell.An example of the patterning method is shown schematically in FIG. 1Athrough FIG. 1C. The resulting flow cell surface (shown in FIG. 2 )includes a substrate and a cured, patterned resin on the substrate, thecured, patterned resin including depressions separated by interstitialregions, and the cured, patterned resin having been formed from anexample of the resin composition disclosed herein. Some examples of themethod further include functionalizing the depressions for a particularapplication, such as sequencing. An example of the functionalization ofthe depressions is shown in FIG. 1D and FIG. 1E.

FIG. 1A depicts a substrate 12, and FIG. 1B depicts an example of theresin composition 10 deposited on the substrate 12.

Examples of suitable substrates 12 include epoxy siloxane, glass,modified or functionalized glass, plastics (including acrylics,polystyrene and copolymers of styrene and other materials,polypropylene, polyethylene, polybutylene, polyurethanes,polytetrafluoroethylene (such as TEFLON® from Chemours), cyclicolefins/cyclo-olefin polymers (COP) (such as ZEONOR® from Zeon),polyimides, etc.), nylon (polyamides), ceramics/ceramic oxides, silica,fused silica, or silica-based materials, aluminum silicate, silicon andmodified silicon (e.g., boron doped p+ silicon), silicon nitride(Si₃N₄), silicon oxide (SiO₂), tantalum pentoxide (Ta₂O₅) or othertantalum oxide(s) (TaO_(x)), hafnium oxide (HfO₂), carbon, metals, orthe like. The substrate 12 may also be glass or silicon, with a coatinglayer of tantalum oxide or another ceramic oxide at the surface.

Some examples of the substrate 12 may have a surface-bound silaneattached thereto, which can react with resin composition components toattach the cured resin composition 10′ to the substrate 12. Thissurface-bound silane is an adhesion promotor. An example of an acrylateadhesion promoter is 3-(Trimethoxysilyl)propyl methacrylate:

An example of an epoxy adhesion promoter is a norbornene silane, such as[(5-bicyclo[2.2.1]hept-2-enyl)ethyl]trimethoxysilane.

In an example, the substrate 12 may be a circular sheet, a panel, awafer, a die etc. having a diameter ranging from about 2 mm to about 300mm, e.g., from about 200 mm to about 300 mm, or may be a rectangularsheet, panel, wafer, die etc. having its largest dimension up to about10 feet (˜3 meters). As one example, a die may have a width ranging fromabout 0.1 mm to about 10 mm. While example dimensions have beenprovided, it is to be understood that the substrate 12 may have anysuitable dimensions.

The resin composition 10 may be any examples of the resin compositiondescribed herein, including the (meth)acrylate-based resin compositionsor the epoxy-based resin compositions. The resin composition 10 may bedeposited on the substrate 12 using any suitable application technique,which may be manual or automated. As examples, the deposition of theresin composition 10 may be performed using vapor deposition techniques,coating techniques, grafting techniques, or the like. Some specificexamples include chemical vapor deposition (CVD), spray coating (e.g.,ultrasonic spray coating), spin coating, dunk or dip coating, doctorblade coating, puddle dispensing, aerosol printing, screen printing,microcontact printing, inkjet printing, or the like. In one example,spin coating is used.

The deposited resin composition 10 is then patterned, using any suitablepatterning technique. In the example shown in FIG. 1B, nanoimprintlithography is used to pattern the resin composition 10. After the resincomposition 10 is deposited, it may be softbaked to remove excesssolvent and/or improve resin composition/substrate adhesion. Whenperformed, the softbake may take place after the resin composition 10 isdeposited and before the working stamp 14 is positioned therein, and ata relatively low temperature, ranging from about 50° C. to about 150°C., for greater than 0 seconds to about 3 minutes. In an example, thesoftbake time ranges from about 30 seconds to about 2.5 minutes.

As illustrated in FIG. 1B, a nanoimprint lithography imprintingapparatus 14 (e.g., a mold or working stamp) is pressed or rolledagainst the layer of the resin composition 10 to create an imprint onthe resin composition 10. The imprinting apparatus 14 includes atemplate of the desired pattern that is to be transferred to the resincomposition 10. Thus, the resin composition 10 is indented or perforatedby the protrusions 16 of the working stamp 14. The protrusions 16 are anegative replica of the depressions or other features that are to beformed in the resin composition 10. The resin composition 10 may be thenbe cured with the working stamp 14 in place.

For some of the resin compositions 10 disclosed herein (i.e., any of theultraviolet light curable resin compositions), curing may beaccomplished by exposing the nanoimprinted, deposited resin composition10 to incident light at a suitable energy dose (e.g., ranging from about0.5 J to about 10 J) for 60 seconds or less. The incident light may beactinic radiation, such as ultraviolet (UV) radiation. In one example,the majority of the UV radiation emitted may have a wavelength of about365 nm.

For some of the resin compositions 10 disclosed herein (i.e., any of thethermally curable resin compositions), curing may be accomplished byexposing the nanoimprinted, deposited resin composition 10 to heat at asuitable temperature (e.g., ranging from about 30° C. to about 150° C.)for 60 seconds or less. Any suitable heater, such as a hot plate,heating lamp, oven, etc. may be used. In one example, the heat isgenerated using a hot plate that the substrate 12 is positioned on.

In the examples disclosed herein, the light or heat energy exposureinitiates polymerization and crosslinking of the monomers in the resincomposition 10. With the effective extent of curing of the resincompositions 10 set forth herein, the incident light or heat exposuretime may be 60 seconds or less. In some instances, the incident light orheat exposure time may be 30 seconds or less. In still other instances,the incident light or heat exposure time may be about 20 seconds. Thecuring process may include a single UV exposure stage or a singleheating event.

After curing, the imprinting apparatus 14 may be removed. Upon releaseof the imprinting apparatus 14, topographic features, e.g., thedepressions 18, are defined in the resin composition 10. The resincomposition 10 having the depressions 18 defined therein is referred toas the cured, patterned resin 10′ (shown in FIG. 1C).

Due, at least in part, to the efficient photo or thermal polymerizationof the resin compositions 10 disclosed herein, the method disclosedherein may not involve a post curing hardbake step in order to attainwell-cured films. In some instances, it may be desirable to perform thepost curing hardbake. It is to be understood that the working stamp 14is released/detached before the hardbake (if performed), e.g., so thatthe working stamp 14 does not bond to the cured, patterned resincomposition 10′. The duration of the hardbake may last from about 5seconds to about 10 minutes at a temperature ranging from about 100° C.to about 300° C. Hardbaking may be performed, for example, to removeresidual solvent(s) from the cured, patterned resin composition 10′, tofurther polymerization of some of the resin composition material(s) (andthus enhance the extent of curing), to improve adhesion and/ormechanical properties, and/or to further reduce the autofluorescence.Any of the heating devices set forth herein may be used for hardbaking.

The chemical make-up of the cured, patterned resin 10′ depends upon theresin composition 10 that is used.

As shown in FIG. 1C, the cured, patterned resin 10′ includes thedepressions 18 defined therein, and interstitial regions 20 separatingadjacent depressions 18. In the examples disclosed herein, thedepressions 18 become functionalized with a polymeric hydrogel 22 (FIG.1D and FIG. 1E) and primers 24, 26 (FIG. 1E and FIG. 2 ), while portionsof the interstitial regions 20 may be used for bonding but will not havethe polymeric hydrogel 22 or the primer(s) 24, 26 thereon.

Many different layouts of the depressions 18 may be envisaged, includingregular, repeating, and non-regular patterns. In an example, thedepressions 18 are disposed in a hexagonal grid for close packing andimproved density. Other layouts may include, for example, rectangularlayouts (e.g., lines or trenches), triangular layouts, and so forth. Insome examples, the layout or pattern can be an x-y format of depressions18 that are in rows and columns. In some other examples, the layout orpattern can be a repeating arrangement of depressions 18 and/orinterstitial regions 20. In still other examples, the layout or patterncan be a random arrangement of depressions 18 and/or interstitialregions 20. The pattern may include stripes, swirls, lines, triangles,rectangles, circles, arcs, checks, plaids, diagonals, arrows, squares,and/or cross-hatches. In an example, the depressions 18 are wellsarranged in rows and columns, as shown in FIG. 1C.

The layout or pattern of the depressions 18 may be characterized withrespect to the density of the depressions 18 (i.e., number ofdepressions 18) in a defined area. For example, the depressions 18 maybe present at a density of approximately 2 million per mm². The densitymay be tuned to different densities including, for example, a density ofat least about 100 per mm², about 1,000 per mm², about 0.1 million permm², about 1 million per mm², about 2 million per mm², about 5 millionper mm², about 10 million per mm², about 50 million per mm², or more, orless. It is to be further understood that the density of depressions 18in the cured, patterned resin 10′ can be between one of the lower valuesand one of the upper values selected from the ranges above. As examples,a high density array may be characterized as having depressions 18separated by less than about 100 nm, a medium density array may becharacterized as having depressions 18 separated by about 400 nm toabout 1 μm, and a low density array may be characterized as havingdepressions 18 separated by greater than about 1 μm. While exampledensities have been provided, it is to be understood that substrateswith any suitable densities may be used.

The layout or pattern of the depressions 18 may also or alternatively becharacterized in terms of the average pitch, i.e., the spacing from thecenter of the depression 18 to the center of an adjacent depression 18(center-to-center spacing) or from the right edge of one depression 18to the left edge of an adjacent depression 18 (edge-to-edge spacing).The pattern can be regular, such that the coefficient of variationaround the average pitch is small, or the pattern can be non-regular inwhich case the coefficient of variation can be relatively large. Ineither case, the average pitch can be, for example, at least about 10nm, about 50 nm, about 0.1 μm, about 0.5 μm, about 1 μm, about 5 μm,about 10 μm, about 100 μm, or more, or less. The average pitch for aparticular pattern of depressions 18 can be between one of the lowervalues and one of the upper values selected from the ranges above. In anexample, the depressions 18 have a pitch (center-to-center spacing) ofabout 1.5 μm. While example average pitch values have been provided, itis to be understood that other average pitch values may be used.

The size of each depression 18 may be characterized by its volume,opening area, depth, and/or diameter.

Each depression 18 can have any volume that is capable of confining afluid. The minimum or maximum volume can be selected, for example, toaccommodate the throughput (e.g., multiplexity), resolution,nucleotides, or analyte reactivity expected for downstream uses of theflow cell. For example, the volume can be at least about 1×10⁻³ μm³,about 1×10⁻² μm³, about 0.1 μm³, about 1 μm³, about 10 μm³, about 100μm³, or more, or less. It is to be understood that the polymerichydrogel 22 can fill all or part of the volume of a depression 18.

The area occupied by each depression opening can be selected based uponsimilar criteria as those set forth above for well volume. For example,the area for each depression opening can be at least about 1×10⁻³ μm²,about 1×10⁻² μm², about 0.1 μm², about 1 μm², about 10 μm², about 100μm², or more, or less. The area occupied by each depression opening canbe greater than, less than or between the values specified above.

The depth of each depression 18 can be large enough to house some of thepolymeric hydrogel 22. In an example, the depth may be about 0.1 μm,about 0.5 μm, about 1 μm, about 10 μm, about 100 μm, or more, or less.In some examples, the depth is about 0.4 μm. The depth of eachdepression 18 can be greater than, less than or between the valuesspecified above.

In some instances, the diameter or length and width of each depression18 can be about 50 nm, about 0.1 μm, about 0.5 μm, about 1 μm, about 10μm, about 100 μm, or more, or less. The diameter or length and width ofeach depression 18 can be greater than, less than or between the valuesspecified above.

After the resin composition 10 is patterned and cured, the cured,patterned resin 10′ may be treated to prepare the surface forapplication of a polymeric hydrogel 22.

In an example, the cured, patterned resin 10′ may be exposed tosilanization, which attaches a silane or the silane derivative to thecured, patterned resin 10′. Silanization introduces the silane or thesilane derivative across the surface, including in the depressions 18(e.g., on the bottom surface and along the side walls) and on theinterstitial regions 20.

Silanization may be accomplished using any silane or silane derivative.The selection of the silane or silane derivative may depend, in part,upon the functionalized molecule that is to be used to form thepolymeric hydrogel 22 (shown in FIG. 2D), as it may be desirable to forma covalent bond between the silane or silane derivative and thepolymeric hydrogel 22. The method used to attach the silane or silanederivative to the cured, patterned resin 10′ may vary depending upon thesilane or silane derivative that is being used. Several examples are setforth herein.

Examples of suitable silanization methods include vapor deposition, spincoating, or other deposition methods. Some examples of methods andmaterials that may be used to silanize the cured, patterned resin 10′are described herein, although it is to be understood that other methodsand materials may be used.

The attachment of the silane or silane derivative forms a pre-treated(e.g., silanized) cured, patterned resin 10′, which includes silanizeddepressions and silanized interstitial regions.

In other examples, the cured, patterned resin 10′ may not be exposed tosilanization. Rather, the cured, patterned resin 10′ may be exposed toplasma ashing, and then the polymeric hydrogel 22 may be directly spincoated (or otherwise deposited) on the plasma ashed cured, patternedresin 10′. In this example, plasma ashing may generatesurface-activating agent(s) (e.g., hydroxyl (C—OH or Si—OH) and/orcarboxyl groups) that can adhere the polymeric hydrogel 22 to the cured,patterned resin 10′. In these examples, the polymeric hydrogel 22 isselected so that it reacts with the surface groups generated by plasmaashing.

In still other examples, the cured, patterned resin 10′ may includeunreacted epoxy groups; and thus may not be exposed to silanizationbecause the unreacted epoxy groups can react directly with aminofunctional groups of the polymeric hydrogel 22. In this example, plasmaashing may be performed, e.g., if it is desirable to clean the surfaceof potential contaminants.

The polymeric hydrogel 22 may then be applied to the pre-treated cured,patterned resin 10′ (as shown in FIG. 1D). The polymeric hydrogel 22 maybe any gel material that can swell when liquid is taken up and cancontract when liquid is removed, e.g., by drying. In an example, thepolymeric hydrogel 22 includes an acrylamide copolymer. Some examples ofthe acrylamide copolymer are represented by the following structure (I):

wherein:

R^(A) is selected from the group consisting of azido, optionallysubstituted amino, optionally substituted alkenyl, optionallysubstituted alkyne, halogen, optionally substituted hydrazone,optionally substituted hydrazine, carboxyl, hydroxy, optionallysubstituted tetrazole, optionally substituted tetrazine, nitrile oxide,nitrone, sulfate, and thiol;

R^(B) is H or optionally substituted alkyl;

R^(C), R^(D), and R^(E) are each independently selected from the groupconsisting of H and optionally substituted alkyl;

each of the —(CH₂)_(p)— can be optionally substituted;

p is an integer in the range of 1 to 50;

n is an integer in the range of 1 to 50,000; and

m is an integer in the range of 1 to 100,000.

One specific example of the acrylamide copolymer represented bystructure (I) ispoly(N-(5-azidoacetamidylpentyl)acrylamide-co-acrylamide, PAZAM.

One of ordinary skill in the art will recognize that the arrangement ofthe recurring “n” and “m” features in structure (I) are representative,and the monomeric subunits may be present in any order in the polymerstructure (e.g., random, block, patterned, or a combination thereof).

The molecular weight of the acrylamide copolymer may range from about 5kDa to about 1500 kDa or from about 10 kDa to about 1000 kDa, or may be,in a specific example, about 312 kDa.

In some examples, the acrylamide copolymer is a linear polymer. In someother examples, the acrylamide copolymer is a lightly cross-linkedpolymer.

In other examples, the polymeric hydrogel 22 may be a variation ofstructure (I). In one example, the acrylamide unit may be replaced withN,N-dimethylacrylamide (

In this example, the acrylamide unit in structure (I) may be replacedwith,

where R^(D), R^(E), and RF are each H or a C1-C6 alkyl, and R^(G) andR^(H) are each a C1-C6 alkyl (instead of H as is the case with theacrylamide). In this example, q may be an integer in the range of 1 to100,000. In another example, the N,N-dimethylacrylamide may be used inaddition to

the acrylamide unit. In this example, structure (I) may include inaddition to the recurring “n” and “m” features, where R^(D), R^(E), andRF are each H or a C1-C6 alkyl, and R^(G) and R^(H) are each a C1-C6alkyl. In this example, q may be an integer in the range of 1 to100,000.

As another example of the polymeric hydrogel 22, the recurring “n”feature in structure (I) may be replaced with a monomer including aheterocyclic azido group having structure (II):

wherein R¹ is H or a C1-C6 alkyl; R₂ is H or a C1-C6 alkyl; L is alinker including a linear chain with 2 to 20 atoms selected from thegroup consisting of carbon, oxygen, and nitrogen and 10 optionalsubstituents on the carbon and any nitrogen atoms in the chain; E is alinear chain including 1 to 4 atoms selected from the group consistingof carbon, oxygen and nitrogen, and optional substituents on the carbonand any nitrogen atoms in the chain; A is an N substituted amide with anH or a C1-C4 alkyl attached to the N; and Z is a nitrogen containingheterocycle. Examples of Z include 5 to 10 carbon-containing ringmembers present as a single cyclic structure or a fused structure. Somespecific examples of Z include pyrrolidinyl, pyridinyl, or pyrimidinyl.As still another example, the gel material may include a recurring unitof each of structure (III) and (IV):

wherein each of R^(1a), R^(2a), R^(1b) and R^(2b) is independentlyselected from hydrogen, an optionally substituted alkyl or optionallysubstituted phenyl; each of R^(3a) and R^(3b) is independently selectedfrom hydrogen, an optionally substituted alkyl, an optionallysubstituted phenyl, or an optionally substituted C7-C14 aralkyl; andeach L¹ and L² is independently selected from an optionally substitutedalkylene linker or an optionally substituted heteroalkylene linker.

In still another example, the acrylamide copolymer is formed usingnitroxide mediated polymerization, and thus at least some of thecopolymer chains have an alkoxyamine end group. In the copolymer chain,the term “alkoxyamine end group” refers to the dormant species —ONR₁R₂,where each of R₁ and R₂ may be the same or different, and mayindependently be a linear or branched alkyl, or a ring structure, andwhere the oxygen atom is attached to the rest of the copolymer chain. Insome examples, the alkoxyamine may also be introduced into some of therecurring acrylamide monomers, e.g., at position R^(A) in structure (I).As such, in one example, structure (I) includes an alkoxyamine endgroup; and in another example, structure (I) includes an alkoxyamine endgroup and alkoxyamine groups in at least some of the side chains.

It is to be understood that other molecules may be used as the polymerichydrogel 22, as long as they are capable of being functionalized withthe desired chemistry, e.g., primers 24, 26. Some examples of suitablematerials for the polymeric hydrogel 22 include functionalized silanes,such as norbornene silane, azido silane, alkyne functionalized silane,amine functionalized silane, maleimide silane, or any other silanehaving functional groups that can respectively attach the desiredchemistry. Still other examples of suitable materials for the polymerichydrogel 22 include those having a colloidal structure, such as agarose;or a polymer mesh structure, such as gelatin; or a cross-linked polymerstructure, such as polyacrylamide polymers and copolymers, silane freeacrylamide (SFA), or an azidolyzed version of SFA. Examples of suitablepolyacrylamide polymers may be synthesized from acrylamide and anacrylic acid or an acrylic acid containing a vinyl group, or frommonomers that form [2+2] photo-cycloaddition reactions. Still otherexamples of suitable materials for the polymeric hydrogel 22 includemixed copolymers of acrylamides and acrylates. A variety of polymerarchitectures containing acrylic monomers (e.g., acrylamides, acrylatesetc.) may be utilized in the examples disclosed herein, such as branchedpolymers, including dendrimers (e.g., multi-arm or star polymers), andthe like. For example, the monomers (e.g., acrylamide, acrylamidecontaining the catalyst, etc.) may be incorporated, either randomly orin block, into the branches (arms) of a dendrimer.

The polymeric hydrogel 22 may be deposited on the surface of thepre-treated cured, patterned resin 10′ using spin coating, or dipping ordip coating, or flow of the functionalized molecule under positive ornegative pressure, or another suitable technique. The polymeric hydrogel22 may be present in a mixture. In an example, the mixture includesPAZAM in water or in an ethanol and water mixture.

After being coated, the polymeric hydrogel 22 may also be exposed to acuring process to form a coating of the polymeric hydrogel 22 across theentire patterned substrate (i.e., in depression(s) 18 and oninterstitial region(s) 20). In an example, curing the polymeric hydrogel22 may take place at a temperature ranging from room temperature (e.g.,about 25° C.) to about 95° C. for a time ranging from about 1millisecond to about several days. In another example, the time mayrange from 10 seconds to at least 24 hours. In still another example,the time may range from about 5 minutes to about 2 hours.

The attachment of the polymeric hydrogel 22 to the depressions 18 andinterstitial regions 20 may be through covalent bonding. The covalentlinking of the polymeric hydrogel 22 to the silanized or plasma asheddepressions is helpful for maintaining the polymeric hydrogel 22 in thedepressions 18 throughout the lifetime of the ultimately formed flowcell during a variety of uses. The following are some examples ofreactions that can take place between the silane or silane derivativeand the polymeric hydrogel 22.

When the silane or silane derivative includes norbornene or a norbornenederivative as the unsaturated moiety, the norbornene or a norbornenederivative can: i) undergo a 1,3-dipolar cycloaddition reaction with anazide/azido group of PAZAM; ii) undergo a coupling reaction with atetrazine group attached to PAZAM; undergo a cycloaddition reaction witha hydrazone group attached to PAZAM; undergo a photo-click reaction witha tetrazole group attached to PAZAM; or undergo a cycloaddition with anitrile oxide group attached to PAZAM.

When the silane or silane derivative includes cyclooctyne or acyclooctyne derivative as the unsaturated moiety, the cyclooctyne orcyclooctyne derivative can: i) undergo a strain-promoted azide-alkyne1,3-cycloaddition (SPAAC) reaction with an azide/azido of PAZAM, or ii)undergo a strain-promoted alkyne-nitrile oxide cycloaddition reactionwith a nitrile oxide group attached to PAZAM.

When the silane or silane derivative includes a bicyclononyne as theunsaturated moiety, the bicyclononyne can undergo similar SPAAC alkynecycloaddition with azides or nitrile oxides attached to PAZAM due to thestrain in the bicyclic ring system.

To form the polymeric hydrogel 22 in the depression(s) 18 and not on theinterstitial region(s) 20 of the cured, patterned resin 10′, thepolymeric hydrogel 22 may be polished off of the interstitial regions20. The polishing process may be performed with a chemical slurry(including, e.g., an abrasive, a buffer, a chelating agent, asurfactant, and/or a dispersant) which can remove the polymeric hydrogel22 from the interstitial regions 20 without deleteriously affecting theunderlying cured, patterned resin 10′ and/or substrate 12 at thoseregions. Alternatively, polishing may be performed with a solution thatdoes not include the abrasive particles. The chemical slurry may be usedin a chemical mechanical polishing system. In this example, polishinghead(s)/pad(s) or other polishing tool(s) is/are capable of polishingthe polymeric hydrogel 22 from the interstitial regions 20 while leavingthe polymeric hydrogel 22 in the depressions 18 and leaving theunderlying cured, patterned resin 10′ at least substantially intact. Asan example, the polishing head may be a Strasbaugh ViPRR II polishinghead. In another example, polishing may be performed with a polishingpad and a solution without any abrasive. For example, the polish pad maybe utilized with a solution free of the abrasive particle (e.g., asolution that does not include abrasive particles).

FIG. 1D depicts the polymeric hydrogel 22 in the depressions 18 and noton the interstitial regions 20. A cleaning process may then beperformed. This process may utilize a water bath and sonication. Thewater bath may be maintained at a relatively low temperature rangingfrom about 22° C. to about 30° C. The silanized, coated, and polishedpatterned substrate may also be spin dried, or dried via anothersuitable technique.

As shown in FIG. 1E, a grafting process is performed in order to graftprimer(s) 24, 26 to the polymeric hydrogel 22 in the depression(s) 19.The primers 24, 26 may be any forward amplification primer and/orreverse amplification primer. In this example, the primers 24, 26 aretwo different primers.

It is desirable for the primers 24, 26 to be immobilized to thepolymeric hydrogel 22. In some examples, immobilization may be by singlepoint covalent attachment to the polymeric hydrogel 22 at the 5′ end ofthe respective primers 24, 26. Any suitable covalent attachment meansknown in the art may be used. In some examples, immobilization may be bystrong non-covalent attachment (e.g., biotin-streptavidin).

Each of the primers 24, 26 has a universal sequence for capture and/oramplification purposes. As examples, the primers 24, 26 may include P5and P7 primers, P15 and P7 primers, or any combination of the PAprimers, the PB primers, the PC primers, and the PD primers set forthherein. As examples, the primers 24, 26 may include any two PA, PB, PC,and PD primers, or any combination of one PA primer and one PB, PC, orPD primer, or any combination of one PB primer and one PC or PD primer,or any combination of one PC primer and one PD primer.

Examples of P5 and P7 primers are used on the surface of commercial flowcells sold by Illumina Inc. for sequencing, for example, on HISEQ™,HISEQX™, MISEQ™, MISEQDX™, MINISEQ™, NEXTSEQ™, NEXTSEQDX™, NOVASEQ™,ISEQ™, GENOME ANALYZER™, and other instrument platforms. The P5 primeris:

P5: 5′→3′

(SEQ. ID. NO. 1) AATGATACGGCGACCACCGAGAUCTACACThe P7 primer may be any of the following:

P7 #1: 5′→3′

(SEQ. ID. NO. 2) CAAGCAGAAGACGGCATACGAnAT

P7 #2: 5′→3′

(SEQ. ID. NO. 3) CAAGCAGAAGACGGCATACnAGATwhere “n” is 8-oxoguanine in each of the sequences.The P15 primer is:

P15: 5′→3′

(SEQ. ID. NO. 4) AATGATACGGCGACCACCGAGAnCTACACwhere “n” is allyl-T.The other primers (PA-PD) mentioned above include:

PA 5′→3′

(SEQ. ID. NO. 5) GCTGGCACGTCCGAACGCTTCGTTAATCCGTTGAG

PB 5′→3′

(SEQ. ID. NO. 6) CGTCGTCTGCCATGGCGCTTCGGTGGATATGAACT

PC 5′→3′

(SEQ. ID. NO. 7) ACGGCCGCTAATATCAACGCGTCGAATCCGCAACT

PD 5′→3′

(SEQ. ID. NO. 8) GCCGCGTTACGTTAGCCGGACTATTCGATGCAGCThe P5, P7, and P15 sequences illustrate the cleavage sites. While notshown in the example sequences for PA-PD, it is to be understood thatany of these primers may include a cleavage site, such as uracil,8-oxoguanine, allyl-T, etc. at any point in the strand. In any of theexamples, the cleavage sites of the primers 24, 26 should be differentfrom each other so that cleavage of the primers 24, 26 does not takeplace at the same time. Examples of suitable cleavage sites includeenzymatically cleavable nucleobases or chemically cleavable nucleobases,modified nucleobases, or linkers (e.g., between nucleobases). Theenzymatically cleavable nucleobase may be susceptible to cleavage byreaction with a glycosylase and an endonuclease, or with an exonuclease.One specific example of the cleavable nucleobase is deoxyuracil (dU),which can be targeted by the USER enzyme. In an example, the uracil basemay be incorporated at the 7^(th) base position from the 3′ end of theP5 primer (P5U) or of the P7 primer (P7U). Other abasic sites may alsobe used. Examples of the chemically cleavable nucleobases, modifiednucleobases, or linkers include 8-oxoguanine, a vicinal diol, adisulfide, a silane, an azobenzene, a photocleavable group, allyl T (athymine nucleotide analog having an allyl functionality), allyl ethers,or an azido functional ether.

Each of the primers disclosed herein may also include a polyT sequenceat the 5′ end of the primer sequence. In some examples, the polyT regionincludes from 2 T bases to 20 T bases. As specific examples, the polyTregion may include 3, 4, 5, 6, 7, or 10 T bases.

The 5′ end of each primer may also include a linker. Any linker thatincludes a terminal alkyne group or another suitable terminal functionalgroup that can attach to the surface functional groups of the polymerichydrogel 22 may be used. Examples of suitable terminal functional groupincluding a tetrazine, an azido, an amino, an epoxy or glycidyl, athiophosphate, a thiol, an aldehyde, a hydrazine, a phosphoramidite, atriazolinedione, or biotin. In one example, the primers 24, 26 areterminated with hexynyl. In some specific examples, a succinimidyl (NHS)ester terminated primer may be reacted with an amine at a surface of thepolymeric hydrogel 22, an aldehyde terminated primer may be reacted witha hydrazine at a surface of the polymeric hydrogel 22, or an alkyneterminated primer may be reacted with an azide at a surface of thepolymeric hydrogel 22, or an azide terminated primer may be reacted withan alkyne or DBCO (dibenzocyclooctyne) at a surface of the polymerichydrogel 22, or an amino terminated primer may be reacted with anactivated carboxylate group or NHS ester at a surface of the polymerichydrogel 22, or a thiol terminated primer may be reacted with analkylating reactant (e.g., iodoacetamine or maleimide) at a surface ofthe polymeric hydrogel 22, a phosphoramidite terminated primer may bereacted with a thioether at a surface of the polymeric hydrogel 22, or abiotin-modified primer may be reacted with streptavidin at a surface ofthe polymeric hydrogel 22.

In an example, grafting of the primers 24, 26 may be accomplished byflow through deposition (e.g., using a temporarily bound lid), dunkcoating, spray coating, puddle dispensing, or by another suitable methodthat will attach the primer(s) 24, 26 to the polymeric hydrogel 22. Eachof these example techniques may utilize a primer solution or mixture,which may include the primer(s) 24, 24′, water, a buffer, and acatalyst.

Dunk coating may involve submerging the flow cell precursor (shown inFIG. 1D) into a series of temperature controlled baths. The baths mayalso be flow controlled and/or covered with a nitrogen blanket. Thebaths may include the primer solution or mixture. Throughout the variousbaths, the primer(s) 24, 26 will attach to the primer-graftingfunctional group(s) of the polymeric hydrogel 22 in at least some of thedepression(s) 18. In an example, the flow cell precursor will beintroduced into a first bath including the primer solution or mixturewhere a reaction takes place to attach the primer(s) 24, 26, and thenmoved to additional baths for washing. Movement from bath to bath mayinvolve a robotic arm or may be performed manually. A drying system mayalso be used in dunk coating.

Spray coating may be accomplished by spraying the primer solution ormixture directly onto the flow cell precursor. The spray coated wafermay be incubated for a time ranging from about 4 minutes to about 60minutes at a temperature ranging from about 0° C. to about 70° C. Afterincubation, the primer solution or mixture may be diluted and removedusing, for example, a spin coater.

Puddle dispensing may be performed according to a pool and spin offmethod, and thus may be accomplished with a spin coater. The primersolution or mixture may be applied (manually or via an automatedprocess) to the flow cell precursor. The applied primer solution ormixture may be applied to or spread across the entire surface of theflow cell precursor. The primer coated flow cell precursor may beincubated for a time ranging from about 2 minutes to about 60 minutes ata temperature ranging from about 0° C. to about 80° C. After incubation,the primer solution or mixture may be diluted and removed using, forexample, the spin coater.

In other example, the primers 24, 26 may be pre-grafted to the polymerichydrogel 22, and thus may be present in the depressions 18 once thepolymeric hydrogel 22 is applied.

FIG. 1E and FIG. 2 illustrate an example of the flow cell surface afterprimer 24, 26 grafting.

The examples shown in FIGS. 1E and 2 are examples of the flow cellsurface without a lid or other flow cell surface bonded thereto. In anexample, the lid may be bonded to at least a portion of the cured,patterned resin 10′, e.g., at some of the interstitial regions 20. Thebond that is formed between the lid and the cured, patterned resin 10′may be a chemical bond, or a mechanical bond (e.g., using a fastener,etc.).

The lid may be any material that is transparent to an excitation lightthat is directed toward the substrate 12 and the cured, patterned resin10′. As examples, the lid may be glass (e.g., borosilicate, fusedsilica, etc.), plastic, or the like. A commercially available example ofa suitable borosilicate glass is D 263®, available from Schott NorthAmerica, Inc. Commercially available examples of suitable plasticmaterials, namely cyclo olefin polymers, are the ZEONOR® productsavailable from Zeon Chemicals L.P.

The lid may be bonded to the cured, patterned resin 10′ using anysuitable technique, such as laser bonding, diffusion bonding, anodicbonding, eutectic bonding, plasma activation bonding, glass fritbonding, or others methods known in the art. In an example, a spacerlayer may be used to bond the lid to the cured, patterned resin 10′. Thespacer layer may be any material that will seal at least some of thecured, patterned resin 10′ and the lid together. In some examples, thespacer layer can be a radiation-absorbing material that aids in bondingof the cured, patterned resin 10′ and the lid.

In other examples, two of the flow cells surfaces (shown in FIG. 1E andFIG. 2 ) may be bonded together so that the depressions 18 face a flowchannel formed therebetween. The flow cells may be bonded atinterstitial regions 20 using similar techniques and materials describedherein for bonding the lid.

One example of the flow cell disclosed herein includes at least one flowcell surface that comprises the substrate 12; and the cured, patternedresin 10′ on the substrate 12, the cured, patterned resin 10′ includingdepressions 18 separated by interstitial regions 20, and the cured,patterned resin 10′ including a cured form of a resin composition 10including: a predetermined mass ratio of a (meth)acrylate cyclosiloxanemonomer and a non-siloxane (meth)acrylate based monomer ranging fromabout >0:<100 to about 80:20; from 0 mass % to about 10 mass %, based ona total solids content of the resin composition, of an initiatorselected from the group consisting of an azo-initiator, an acetophenone,a phosphine oxide, a brominated aromatic acrylate, and adithiocarbamate; a surface additive; and a solvent; wherein the cured,patterned resin 10′ has low or no autofluorescence when exposed toviolet or blue excitation wavelengths ranging from about 375 nm to about500 nm.

Another example of the flow cell disclosed herein includes at least oneflow cell surface that comprises the substrate 12; and the cured,patterned resin 10′ on the substrate 12, the cured, patterned resin 10′including depressions 18 separated by interstitial regions 20, and thecured, patterned resin 10′ including a cured form of a resin composition10 including: a predetermined mass ratio of a first epoxy cyclosiloxanemonomer having a 1:1 ratio of Si:O in the cyclosiloxane and a secondepoxy cyclosiloxane monomer having a 1:1 ratio of Si:O in thecyclosiloxane, wherein the first and second epoxy cyclosiloxane monomersare different, and wherein the predetermined mass ratio ranges fromabout 3:7 to about 7:3; bis-(4-methylphenyl)iodonium hexafluorophosphateas a first initiator; a second initiator selected from the groupconsisting of a free radical initiator and a cationic initiator otherthan bis-(4-methylphenyl)iodonium hexafluorophosphate; a surfaceadditive; and a solvent; wherein the cured, patterned resin 10′ has lowor no autofluorescence when exposed to violet or blue excitationwavelengths ranging from about 375 nm to about 500 nm.

Methods for Using the Flow Cell

The flow cells disclosed herein may be used in a variety of sequencingapproaches or technologies, including techniques often referred to assequencing-by-synthesis (SBS), cyclic-array sequencing,sequencing-by-ligation, pyrosequencing, and so forth. With any of thesetechniques, since the polymeric hydrogel 22 and attached primer(s) 24,26 are present in the depressions 18 and not on the interstitial regions20, amplification will be confined to the depressions.

As one example, a sequencing by synthesis (SBS) reaction may be run on asystem such as the HISEQ™, HISEQX™, MISEQ™, MISEQDX™, MINISEQ™,NOVASEQ™, ISEQ™, NEXTSEQDX™, or NEXTSEQ™ sequencer systems from Illumina(San Diego, Calif.). In SBS, extension of a nucleic acid primer (e.g., asequencing primer) along a nucleic acid template (i.e., the sequencingtemplate) is monitored to determine the sequence of nucleotides in thetemplate. The underlying chemical process can be polymerization (e.g.,catalyzed by a polymerase enzyme) or ligation (e.g., catalyzed by aligase enzyme). In a particular polymerase-based SBS process,fluorescently labeled nucleotides are added to the sequencing primer(thereby extending the sequencing primer) in a template dependentfashion such that detection of the order and type of nucleotides addedto the sequencing primer can be used to determine the sequence of thetemplate.

Prior to sequencing, the capture and amplification primers 24, 26 can beexposed to a sequencing library, which is amplified using any suitablemethod, such as cluster generation.

In one example of cluster generation, the library fragments are copiedfrom the hybridized primers 24, 26 by 3′ extension using a high-fidelityDNA polymerase. The original library fragments are denatured, leavingthe copies immobilized. Isothermal bridge amplification may be used toamplify the immobilized copies. For example, the copied templates loopover to hybridize to an adjacent, complementary primer 24, 26 and apolymerase copies the copied templates to form double stranded bridges,which are denatured to form two single stranded strands. These twostrands loop over and hybridize to adjacent, complementary primers 24,26 and are extended again to form two new double stranded loops. Theprocess is repeated on each template copy by cycles of isothermaldenaturation and amplification to create dense clonal clusters. Eachcluster of double stranded bridges is denatured. In an example, thereverse strand is removed by specific base cleavage, leaving forwardtemplate polynucleotide strands. Clustering results in the formation ofseveral template polynucleotide strands in each of the depressions 18.This example of clustering is bridge amplification, and is one exampleof the amplification that may be performed. It is to be understood thatother amplification techniques may be used, such as the exclusionamplification (Examp) workflow (Illumina Inc.).

A sequencing primer may be introduced that hybridizes to a complementarysequence on the template polynucleotide strand. This sequencing primerrenders the template polynucleotide strand ready for sequencing. The3′-ends of the templates and any flow cell-bound primers 24, 26 (notattached to the copy) may be blocked to prevent interference with thesequencing reaction, and in particular, to prevent undesirable priming.

To initiate sequencing, an incorporation mix may be added to the flowcell. In one example, the incorporation mix includes a liquid carrier, apolymerase, and fluorescently labeled nucleotides. The fluorescentlylabeled nucleotides may include a 3′ OH blocking group. When theincorporation mix is introduced into the flow cell, the fluid enters aflow channel and flows into the depressions 18 (where the templatepolynucleotide strands are present).

The fluorescently labeled nucleotides are added to the sequencing primer(thereby extending the sequencing primer) by the polymerase in atemplate dependent fashion such that detection of the order and type ofnucleotides added to the sequencing primer can be used to determine thesequence of the template. More particularly, one of the nucleotides isincorporated, by a respective polymerase, into a nascent strand thatextends the sequencing primer and that is complementary to the templatepolynucleotide strand. In other words, in at least some of the templatepolynucleotide strands across the flow cell, respective polymerasesextend the hybridized sequencing primer by one of the nucleotides in theincorporation mix.

The incorporation of the nucleotides can be detected through an imagingevent. During an imaging event, an illumination system (not shown) mayprovide an excitation light to the flow cell surface(s).

In some examples, the nucleotides can further include a reversibletermination property (e.g., the 3′ OH blocking group) that terminatesfurther primer extension once a nucleotide has been added to thesequencing primer. For example, a nucleotide analog having a reversibleterminator moiety can be added to the sequencing primer such thatsubsequent extension cannot occur until a deblocking agent is deliveredto remove the moiety. Thus, for examples that use reversibletermination, a deblocking reagent can be delivered to the flow cellafter detection occurs.

Wash(es) may take place between the various fluid delivery steps. TheSBS cycle can then be repeated n times to extend the sequencing primerby n nucleotides, thereby detecting a sequence of length n.

In some examples, the forward strands may be sequenced and removed, andthen reverse strands are constructed and sequenced as described herein.

While SBS has been described in detail, it is to be understood that theflow cells described herein may be utilized with other sequencingprotocol, for genotyping, or in other chemical and/or biologicalapplications.

While the examples described in FIG. 1A through FIG. 1E and FIG. 2illustrate the use of the example resin compositions 10 in the formationof a flow cell surface, it is to be understood that the resincompositions 10 disclosed herein may be used in other applications wherelow autofluorescence is desired. As one example, the resin composition10, 10′ may be used in any optically-based sequencing technique. Asother examples, the resin composition 10, 10′ may be used in planarwaveguides, in complementary metal-oxide semiconductors (CMOS), etc.

To further illustrate the present disclosure, examples are given herein.It is to be understood that these examples are provided for illustrativepurposes and are not to be construed as limiting the scope of thepresent disclosure.

NON-LIMITING WORKING EXAMPLES

Several example resins, comparative example resins, and control exampleswere prepared and analyzed as described in more detail in each of thefollowing examples.

The autofluorescence was measured with a rig equipped with violet, blueand green channels. The laser power measured at the sample variedbetween 170 mW and 400 mW, the numerical aperture (NA) of the objectivelens ranges between 0.13-0.50, and the slit size ranged between 10 μmand 200 μm. The excitation and the collection wavelengths of the threechannels of the AF rig are shown in Table 1.

TABLE 1 Color Excitation/nm Collection/nm violet 405 418-450 blue 457482-525 green 532 575-625

The efficiency of the UV curing was determined for some examples usingFTIR (Fourier-transform infrared spectroscopy).

The follow abbreviations are used in one or more of the examples:2,4,6,8-tetramethyl-2,4,6,8-tetrakis[3-acryloyloxypropyl]cyclotetrasiloxane:AD4 pentaerythritol tetraacrylate: PE4A glycerol 1,3-diglycerolatediacrylate: GD2A pentaerythritol triacrylate: PE3A glyceroldimethacrylate, mixture of isomers: GD2MA trimethylpropane triacrylate:TMP3A 3-(acryloyloxy)-2-hydroxypropyl methacrylate: HPMMA propyleneglycol methyl ether acetate: PGMEA Azobisiso-butyronitrile: AIBN2,2′-azobis(2,4-dimethylvaleronitrile): V65B2,2-dimethoxy-2-phenylacetophenone: DPA 2-hydroxy-2-methylpriophenone:HMPP diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide: DPBAPOphenylbis(2,4,6-trimethylbenzoyl)phosphine oxide: TMBAPOpentabromobenzyl acrylate: BPPA epoxycyclohexyl tetramethylcyclotetrasiloxane: EC-D4 glycidyl cyclotetrasiloxane: G-D4bis-(4-methylphenyl)iodonium hexafluorophosphate: IPFtris(4-((4-acetylphenyl)thio)phenyl)-sulfoniumtetrakis(perfluoro-phenyl)borate: PAG2904-cyano-4-(phenylcarbonothioylthio)pentanoic acid: RAFT-1 ethylpyruvate: EP bis[4-(tert-butyl)phenyl]iodoniumtetra(nonafluoro-tert-butoxy)aluminate: PITA1,1,2,2-tetraphenyl-1,2-ethanediol: TPED Fully Functional Cytosine: FFCFully Functional Adenine: FFA Fully Funtional Thymine: FFT

Example 1— Initiator Free (Meth)Acrylates

Two example (meth)acrylate-based resins (Ex. Resin 1 and Ex. Resin 2)and one comparative example resin (Comp. Ex. Resin 3) were prepared. Theresin compositions are provided in Table 2 below.

TABLE 2 Ex. Ex. Comp. Ex. Resin 1 Resin 2 Resin 3 (mass % (mass % (mass% Ingredient Specific of total of total of total Type Ingredient solids)solids) solids) (meth)acrylate AD4 49.2 49.2 — cyclosiloxane monomernon-siloxane GD2A — 49.2 — (meth)acrylate PE4A 49.2 — — based monomerEpoxy epoxy — — 92.4  monomer polyhedral oligomeric silsesquioxaneInitiator PAG 290 — — 1.0 IPF — — 5.0 Surface BYK ®-350  1.6  1.6 1.6Additive Solvent PGMEA Added to Added to Added to achieve achieveachieve about 17% about 17% about 18% solids solids solids

Glass wafers were used as the substrates in this example. One bare(untreated and uncoated) glass wafer was used as a control example.

The rest of the glass wafers were pre-treated with an adhesion promotingsilane coupling agent. The adhesion promoter was spin-coated from a 25mass % solution in PGMEA onto glass wafers. A post-coating heattreatment (at 130° C. for 2 minutes) silanized the glass surfaces.

Each of the resin compositions (Ex. Resin 1, Ex. Resin 2, and Comp. Ex.Resin 3) were spin coated on the silanized glass wafers. A working stampwas hand rolled on each of the coated glass wafers. The working stamphad a center-to-center pitch of 624 nm. The resin compositions were thenexposed to UV curing under a 365 nm UV LED light source with a 330mW/cm² power output measured at the sample level. Curing was performedfor 30 seconds. After curing, the working stamp was released and ahardbake was performed for about 2 minutes at a temperature of about200° C.

Each of Ex. Resin 1, Ex. Resin 2, and Comp. Ex. Resin 3 was imprintable.

The autofluorescence of the imprints generated using Ex. Resin 1, Ex.Resin 2, and Comp. Ex. Resin 3 was measured with the rig described abovefor each of the violet, blue and green channels. The control example wasalso tested for comparison. The results are shown in FIG. 3 (depictingFilterArea versus the channel wavelength (nm)). In the respective violet(405 nm), blue (457 nm), and green (532 nm) channels, Ex. Resin 1 andEx. Resin 2 exhibited slightly higher autofluorescence than the controlexample and much lower autofluorescence than Comp. Ex. Resin 3.

Example 2—Azo-Initiator (Meth)Acrylates

Three example (meth)acrylate-based resins (Ex. Resin 4-Ex. Resin 6) wereprepared. One comparative example resin (Comp. Ex. Resin 7) having thesame formulation as Comp. Ex. Resin 3 from Example 1 was also prepared.Ex. Resins 4 and 5 were prepared with azo-initiators, and Ex. Resin 6was similar to Ex. Resin 5 without the initiator (and thus was similarto the initiator free resins of Example 1). The example resincompositions are provided in Table 3 below.

TABLE 3 Ex. Ex. Ex. Resin 4 Resin 5 Resin 6 (mass % (mass % (mass %Specific of total of total of total Ingredient Type Ingredient solids)solids) solids) (meth)acrylate AD4 48.2 48.2 49.2 cyclosiloxane monomernon-siloxane PE3A   48.2 49.2 (meth)acrylate PE4A 48.2     based monomerAzo-initiator AIBN 2.0      V65B   2.0    Surface Additive BYKR-350 1.6 1.6  1.6  Solvent PGMEA Added to Added to Added to achieve achieveachieve about 17% about 17% about 17% solids solids solids

Glass wafers were used as the substrates in this example. One bare(untreated and uncoated) glass wafer was used as a control example.

The rest of the glass wafers were pre-treated with an adhesion promotingsilane coupling agent. The adhesion promoter was spin-coated from a 25mass % solution in PGMEA onto glass wafers. A post-coating heattreatment (at 130° C. for 2 minutes) silanized the glass surfaces.

Some of the resin compositions (Ex. Resin 4 and Comp. Ex. Resin 7) werespin coated on the silanized glass wafers. A working stamp was handrolled on each of the coated glass wafers. The working stamp had acenter-to-center pitch of 624 nm or 350 nm. The resin compositions werethen exposed to UV curing under a 365 nm UV LED light source with a 330mW/cm² power output measured at the sample level. Curing was performedfor 30 seconds. After curing, the working stamp was released and ahardbake was performed for about 2 minutes at a temperature of about200° C.

Each of Ex. Resin 4 and Comp. Ex. Resin 7 was imprintable.

The autofluorescence of the imprints generated using Ex. Resin 4 andComp. Ex. Resin 7 was measured with the rig described above for each ofthe violet, blue and green channels. The control example was also testedfor comparison. The results are shown in FIG. 4 (depicting FilterAreaversus the channel wavelength (nm)). In the respective violet (405 nm),blue (457 nm), and green (532 nm) channels, Ex. Resin 4 exhibitedslightly higher autofluorescence than the control example and generallylower autofluorescence than Comp. Ex. Resin 7.

The other resin compositions (Ex. Resin 5 and Ex. Resin 6) were spincoated on the silanized glass wafers. A working stamp was hand rolled oneach of the coated glass wafers. The working stamp had acenter-to-center pitch of 624 nm or 350 nm. The resin compositions werethen exposed to UV curing under a 365 nm UV LED light source with a 330mW/cm² power output measured at the sample level. Curing was performedfor 10 seconds. After curing, the working stamp was released and ahardbake was performed for about 2 minutes at a temperature of about200° C.

Each of Ex. Resin 5 and Ex. Resin 6 was imprintable.

FTIR spectra of the imprints generated with Ex. Resin 5 (withazo-initiator) and Ex. Resin 6 (without azo-initiator) and of thecontrol example were recorded. These results are shown in FIG. 5A (1406cm⁻¹, C═C—H in-plane deformation) and FIG. 5B (1636 cm⁻¹, CH₂═CH—Rstretching). The intensity decrease of the peaks at 1636 cm⁻¹ and 1406cm⁻¹ was used to monitor the extent of UV curing. As shown in both FIG.5A and FIG. 5B, Ex. Resin 6 (without the azo-initiator) exhibited anincreased extent of cure relative to the control example, and Ex. Resin5 (with the azo-initiator) exhibited an increased extent of curerelative to Ex. Resin 6. These results illustrate that the initiatorfree (meth)acrylate resin compositions, both without and with theazo-initiator, increase the extent of cure.

Example 3—Acetophenone, Phosphine Oxide, Brominated Aromatic Acrylate,and Dithiocarbamate Initiator (Meth)Acrylates

Several example (meth)acrylate-based resins were prepared. Five (Ex.Resin 8-Ex. Resin 12) of the example resins had the same (meth)acrylatemonomers and different initiators. These compositions are provided inTable 4 below. Six additional example resins (Ex. Resin 13-Ex. Resin 18)had the different (meth)acrylate monomers and the same initiator. Thesecompositions are provided in Table 5 below. Two comparative exampleresins (Comp. Ex. Resin 19 and Comp. Ex. Resin 20) were also preparedwith the same formulation as Comp. Ex. Resin 3 from Example 1.

TABLE 4 Ex. Ex. Ex. Ex. Ex. Resin 8 Resin 9 Resin 10 Resin 11 Resin 12(mass % (mass % (mass % (mass % (mass % Ingredient Specific of total oftotal of total of total of total Type Ingredient solids) solids) solids)solids) solids) (meth)acrylate AD4 48.2 48.2 48.2 48.2 48.2cyclosiloxane monomer non-siloxane PE3A 48.2 48.2 48.2 48.2 48.2(meth)acrylate based monomer Acetophenone DPA — — — — 2.0 Initiator HMPP— 2.0 — — — Phosphine DPBAPO 2.0 — — — — Oxide Initiator TMBAPO — — —2.0 — Brominated BPPA — — 2.0 — — aromatic acrylate Surface AdditiveBYK ®-350 1.6 1.6 1.6 1.6 1.6 Solvent PGMEA Added to Added to Added toAdded to Added to achieve achieve achieve achieve achieve about aboutabout about about 17% 17% 17% 17% 17% solids solids solids solids solids

TABLE 5 Ex. Ex. Ex. Ex. Ex. Ex. Resin 13 Resin 14 Resin 15 Resin 16Resin 17 Resin 18 (mass % (mass % (mass % (mass % (mass % (mass %Ingredient Specific of total of total of total of total of total oftotal Type Ingredient solids) solids) solids) solids) solids) solids)(meth)acrylate AD4 48.2 48.2 48.2 48.2 48.2 48.2 cyclosiloxane monomernon-siloxane PE3A 48.2 — — — — — (meth)acrylate GD2A — 48.2 — — — basedPE4A — — 48.2 — — — monomer TMP3A — — — 48.2 — — GD2MA — — — — 48.2 —HPMMA — — — — — 48.2 Phosphine DPBAPO 2.0 2.0 2.0 2.0 2.0 2.0 OxideInitiator Surface Additive BYK ®-350 1.6 1.6 1.6 1.6 1.6 1.6 SolventPGMEA Added Added Added Added Added Added to to to to to to achieveachieve achieve achieve achieve achieve about about about about aboutabout 17% 17% 17% 17% 17% 17% solids solids solids solids solids solids

Glass wafers were used as the substrates in this example. One bare(untreated and uncoated) glass wafer was used as a control example.

The rest of the glass wafers were pre-treated with an adhesion promotingsilane coupling agent. The adhesion promoter was spin-coated from a 25mass % solution in PGMEA onto glass wafers. A post-coating heattreatment (at 130° C. for 2 minutes) silanized the glass surfaces.

All of the resin compositions (Ex. Resin 8-Ex. Resin 18 and Comp. Ex.Resin 19) were spin coated on the silanized glass wafers. A workingstamp was hand rolled on each of the coated glass wafers. The workingstamp had a center-to-center pitch of 624 nm or 350 nm. The resincompositions were then exposed to UV curing under a 365 nm UV LED lightsource with a 330 mW/cm² power output measured at the sample level.Curing was performed for 30 seconds. After curing, the working stamp wasreleased and a hardbake was performed for about 2 minutes at atemperature of about 200° C.

Each of Ex. Resin 8-Ex. Resin 18 and Comp. Ex. Resin 19 was imprintable.

The autofluorescence of the imprints generated using Ex. Resin 8-Ex.Resin 12 (with different initiators) and Comp. Ex. Resin 19 was measuredwith the rig described above for the violet (405 nm) channel. Thecontrol example was also tested for comparison. The results are shown inFIG. 6 (depicting the FilterArea for each of the resins). In the violet(405 nm) channel, Ex. Resin 8 through Ex. Resin 12 exhibited higherautofluorescence than the control example and significantly lowerautofluorescence than Comp. Ex. Resin 19.

The autofluorescence of the imprints generated using Ex. Resin 13-Ex.Resin 18 and Comp. Ex. Resin 20 was measured with the rig describedabove for each of the violet (405 nm), blue (457 nm), and green (532 nm)channels. The control example was also tested for comparison. Theresults are shown in FIG. 7 (depicting FilterArea versus the channelwavelength (nm)). In the respective violet (405 nm) and blue (457 nm)channels, Ex. Resin 13 through Ex. Resin 18 exhibited slightly higherautofluorescence than the control example and significantly lowerautofluorescence than Comp. Ex. Resin 20. The results in FIG. 7 alsodemonstrate that the autofluorescence also depends, in part, on thechoice of the non-siloxane (meth) acrylate based monomer.

Example 4—Comparison of Initiator Free, Azo Initiator, and PhosphineOxide Dithiocarbamate Initiator (Meth)Acrylates

The curing time for Ex. Resin 6 (Example 2, initiator free), Ex. Resin 5(Example 2, azo-initiator), and Ex. Resin 8 (Example 3, phosphine oxideinitiator) were compared because each of these resins was prepared withthe same 1:1 mass ratio of AD4:PE3A. The results are shown in FIG. 8 .Without any initiator, the Ex. Resin 6 cured in about 20 seconds. Theinitiators significantly decreased the curing time to about 2.5 secondswith the phosphine oxide initiator (Ex. Resin 8) and to about 7.5seconds with the azo-initiator (Ex. Resin 5). The results in FIG. 8 werebased upon visual observation and supporting FTIR data.

Example 5—Epoxy Resins

Five example epoxy-based resin compositions were prepared. Each of theseresin compositions (Ex. Resin 20-Ex. Resin 24) was prepared with thesame combination of epoxy monomers and different initiators. Thesecompositions are provided in Table 6 below. A comparative example resins(Comp. Ex. Resin 25) was also prepared with the same formulation asComp. Ex. Resin 3 from Example 1.

TABLE 6 Ex. Ex. Ex. Ex. Ex. Resin 20 Resin 21 Resin 22 Resin 23 Resin 24(mass % (mass % (mass % (mass % (mass % Ingredient Specific of total oftotal of total of total of total Type Ingredient solids) solids) solids)solids) solids) first epoxy EC-D4 46.6 46.2 33.7-45.2 33.7-45.233.7-45.2 cyclosiloxane second epoxy G-D4 46.6 46.2 33.7-45.2 33.7-45.233.7-45.2 cyclosiloxane First Initiator IPF 5.0 5.0 5.0 5.0 5.0 SecondPAG290 0.2 1.0 — — — Initiator EP — —  3.0-26.0 — — PITA — — —  3.0-26.0— TPED — — — — 3.0-26.0 Surface Additive BYK ®-350 1.6 1.6 1.6 1.6 1.6Solvent PGMEA Added to Added to Added to Added to Added to achieveachieve achieve achieve achieve about about about about about 17% 17%17% 17% 17% solids solids solids solids solids

Glass wafers were used as the substrates in this example. One bare(untreated and uncoated) glass wafer was used as a control example.

All of the resin compositions (Ex. Resin 20-Ex. Resin 24 and Comp. Ex.Resin 25) were spin coated on the silanized glass wafers. A softbake wasperformed for about 2 minutes at 130° C. or for about 30 seconds at 90°C. A working stamp was hand rolled on each of the coated glass wafers.The working stamp had a center-to-center pitch of 624 nm or 350 nm. Theresin compositions were then exposed to UV curing under a 365 nm UV LEDlight source with a 330 mW/cm² power output measured at the samplelevel. Curing was performed for 4 seconds (Ex. Resin 21), or for 8seconds (Comp. Ex. Resin 25), or for 16 seconds (Ex. Resin 20), or for60 seconds (Ex. Resin 22-Ex. Resin 24). After curing, the working stampwas released.

Each of Ex. Resin 20-Ex. Resin 24 and Comp. Ex. Resin 25 wasimprintable.

The autofluorescence of the imprints generated using Ex. Resin 20-Ex.Resin 24 (with different initiators) and Comp. Ex. Resin 25 was measuredwith the rig described above for each of the violet (405 nm), blue (457nm), and green (532 nm) channels. The results are shown in FIG. 9(depicting FilterArea versus the channel wavelength (nm)). In therespective violet (405 nm) channel, Ex. Resin 20 through Ex. Resin 24exhibited significantly lower autofluorescence than Comp. Ex. Resin 25.In the blue (457 nm) channel, Ex. Resin 20 and Ex. Resin 21 (with PAG290as the second initiator) exhibited slightly lower autofluorescence thanComp. Ex. Resin 25.

The curing time for Ex. Resin 20 through Ex. Resin 22 were compared. Theresults are shown in FIG. 10 . Ex. Resins 20 and 21, including thecombination of the IPF and PAG290 initiators, exhibited desirably quickcuring times of about 16 seconds and 4 seconds, respectively. While thecuring time of Ex. Resins 22 and 23 was not quite as fast, they bothexhibited cure times of 60 seconds.

FTIR spectra were measured for each of the epoxy resins (Ex. Resin20-Ex. Resin 24). To assess the extent of cure, the intensity of a peakcorresponding to the C—H tension in an unopened epoxy ring at 2991 cm⁻¹was normalized with respect to a reference peak at 2925-2927 cm⁻¹(denoted as corrected Int2991). A lower intensity of this peakcorresponded to a higher extent of cure. FIG. 11 depicts the results.The highlighted area depicts the empirical range of the desired extentof cure to obtain a sufficiently crosslinked resin with a high-quality,non-reflowing imprint. Each of the example resins falls within theempirical range, thus confirming the high quality of the imprints.

Example 6—Sequencing

Non-patterned glass dies were respectively coated with Ex. Resin 22(epoxy-based resin from Example 5), Ex. Resin 8 ((meth)acrylate-basedresin from Example 3), and Comp. Ex. Resin 3 (from Example 1). Each ofthe resin compositions was cured for 60 seconds. A blank glass die wasused as the control example.

All of the dies were ashed in air plasma at 595 W RF power for about 30seconds. The surface-activated dies were silanized using[(5-bicyclo[2.2.1]hept-2-enyl)ethyl]trimethoxysilane in the neatchemical's vapor overnight at 60° C. The dies were bonded to cover slipshaving engraved fluidic channels using an adhesive, which was UV curedfor 9 minutes under a UV lamp with wide spectral emission and a poweroutput of 3 mW measured at the sample level.

The silanized dies in the bonded flow cells were fluidically coated witha 0.175 mass % N,N-dimethyl-acrylamide aqueous solution, which wasincubated for 75 minutes at 70° C. to generate a hydrogel layer. DNAoligomers (P5 and P7 primers) were grafted onto the hydrogel layer froman 18 μM aqueous solution, which was incubated at 60° C. for 30 minutes.

A 0.67 pM PhiX library was used as a DNA template. Cluster generationwas performed using Illumina's MiSeq™ reagents.

12 cycles of sequencing by synthesis (SBS) were performed with anincorporation mix that included fully functional oligonucleotides(unlabeled G, FFC-blue dye label, FFC-violet dye label, FFT violet dyelabel, FFA green dye label, FFA blue dye label (with two different dyesbeing used for the flow cell including Ex. Resin 22 and the flow cellincluding Ex. Resin 8), some of which included dye labels forviolet/blue sequencing. In the 13th cycle, the fluorescent dyes wereremoved from the 3′ blocking group. The 14th cycle consisted of an extrawashing step by flushing through the flow cell with an incorporation mixcontaining no fully functional nucleotides. Finally, in the 15th cycle,the complementary strands were dehybridized from the clusters. Cycles13-15 were included as control runs to verify if the fully functionaloligonucleotides were bound the substrate in off-cluster areas.

IIlumina's MiSeq™ was used for sequencing. The optic settings of theMiSeq™ instrument are shown in Table 7.

TABLE 7 Excitation Collection Irradiance/ Exposure channel wavelength/nmwavelength/nm W cm⁻² time/ms violet 402 418-447.5 71 500 blue 464482-520  236 300

The sequencing data collected included density (K/mm²), passing filter(% PF) (percentage), and the percentage of Qscores that were greaterthan Q30. Density is the number of clusters generated per unit area ofthe flow cell surface. Passing filter (PF) is the metric used todescribe clusters which pass a chastity threshold and are used forfurther processing and analysis of sequencing data. A higher % passingfilter result indicates an increased yield of unique clusters used forsequencing data. A Qscore of 30 (Q30) is equivalent to the probabilityof an incorrect base call 1 in 1000 times. This means that the base callaccuracy (i.e., the probability of a correct base call) is 99.9%. Alower base call accuracy of 99% (Q20) will have an incorrect base callprobability of 1 in 100, meaning that every 100 base pair sequencingread will likely contain an error. When sequencing quality reaches Q30,virtually all of the reads will be perfect, having 99.9% accuracy.

The sequencing data from the twelve sequencing run for each flow cell isreproduced in Table 8.

TABLE 8 Flow Density Clusters Cell ID Resin (K/mm²) PF (%) % ≤ 30 Ex. AEx. Resin 22 247 ± 12 41.87 ± 9.09 50.74 (epoxy-based) Ex. B Ex. Resin 8243 ± 29  46.78 ± 12.82 68.96 ((meth)acrylate based) Comp. C Comp. Resin3 247 ± 9  46.87 ± 3.66 62.47 Control None 195 ± 5  32.26 ± 8.88 64.40

The sequencing data for the example flow cells Ex. A and Ex. Bdemonstrate that the (meth)acrylate and epoxy based resins disclosedherein are compatible with violet/blue sequencing.

ADDITIONAL NOTES

It should be appreciated that all combinations of the foregoing conceptsand additional concepts discussed in greater detail below (provided suchconcepts are not mutually inconsistent) are contemplated as being partof the inventive subject matter disclosed herein. In particular, allcombinations of claimed subject matter appearing at the end of thisdisclosure are contemplated as being part of the inventive subjectmatter disclosed herein. It should also be appreciated that terminologyexplicitly employed herein that also may appear in any disclosureincorporated by reference should be accorded a meaning most consistentwith the particular concepts disclosed herein.

Reference throughout the specification to “one example”, “anotherexample”, “an example”, and so forth, means that a particular element(e.g., feature, structure, and/or characteristic) described inconnection with the example is included in at least one exampledescribed herein, and may or may not be present in other examples. Inaddition, it is to be understood that the described elements for anyexample may be combined in any suitable manner in the various examplesunless the context clearly dictates otherwise.

While several examples have been described in detail, it is to beunderstood that the disclosed examples may be modified. Therefore, theforegoing description is to be considered non-limiting.

1. An ultraviolet light or thermally curable resin composition,consisting of: a predetermined mass ratio of a (meth)acrylatecyclosiloxane monomer and a non-siloxane (meth)acrylate based monomerranging from about >0:<100 to about 80:20; from 0 mass % to about 10mass %, based on a total solids content of the resin composition, of aninitiator selected from the group consisting of an azo-initiator, anacetophenone, a phosphine oxide, a brominated aromatic acrylate, and adithiocarbamate; a surface additive; and a solvent.
 2. The ultravioletlight or thermally curable resin composition as defined in claim 1,wherein: the (meth)acrylate cyclosiloxane monomer is2,4,6,8-tetramethyl-2,4,6,8-tetrakis[3-acryloyloxypropyl]cyclotetrasiloxane;and the non-siloxane (meth)acrylate based monomer is selected from thegroup consisting of glycerol dimethacrylate, mixture of isomers;glycerol 1,3-diglycerolate diacrylate; pentaerythritol triacrylate;pentaerythritol tetraacrylate; bisphenol A glycerolate diacrylate;trimethylpropane triacrylate; 3-(acryloyloxy)-2-hydroxypropylmethacrylate; poly(ethylene glycol) dimethacrylate; ethylene glycoldimethacrylate; and combinations thereof.
 3. The ultraviolet light orthermally curable resin composition as defined in claim 1, wherein: theresin composition includes the initiator; the initiator is theazo-initiator; and the azo-initiator is selected from the groupconsisting of azobisisobutyronitrile;2,2′-azobis(2,4-dimethylvaleronitrile);1,1′-azobis(cyclohexanecarbonitrile);2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile); dimethyl2,2′-azobis(2-methylpropionate); and2,2′-Azobis(N-butyl-2-methylpropionamide.
 4. The ultraviolet light orthermally curable resin composition as defined in claim 1, wherein: theresin composition includes the initiator; the initiator is theacetophenone; and the acetophenone is selected from the group consistingof 2,2-dimethoxy-2-phenylacetophenone and 2-hydroxy-2-methylpriophenone.5. The ultraviolet light or thermally curable resin composition asdefined in claim 1, wherein: the resin composition includes theinitiator; the initiator is the phosphine oxide; and the phosphine oxideis selected from the group consisting ofdiphenyl(2,4,6-trimethylbenzoyl)phosphine oxide,phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide,ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate,diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and combinationsthereof.
 6. The ultraviolet light or thermally curable resin compositionas defined in claim 1, wherein: the resin composition includes theinitiator; the initiator is the brominated aromatic acrylate; and thebrominated aromatic acrylate is pentabromobenzyl acrylate.
 7. Theultraviolet light or thermally curable resin composition as defined inclaim 1, wherein: the resin composition includes the initiator; theinitiator is the dithiocarbamate; and the dithiocarbamate is benzyldiethyldithiocarbamate.
 8. An ultraviolet light or thermally curableresin composition, comprising: a predetermined mass ratio of a(meth)acrylate cyclosiloxane monomer and a non-siloxane (meth)acrylatebased monomer ranging from about >0:<100 to about 80:20; from greaterthan 0 mass % to about 5 mass %, based on a total solids content of theresin composition, of an azo-initiator; a surface additive; and asolvent; wherein the resin composition is free of a photosensitizer. 9.The ultraviolet light or thermally curable resin composition as definedin claim 8, wherein: the (meth)acrylate cyclosiloxane monomer is2,4,6,8-tetramethyl-2,4,6,8-tetrakis[3-acryloyloxypropyl]cyclotetrasiloxane;and the non-siloxane (meth)acrylate based monomer is selected from thegroup consisting of glycerol dimethacrylate, mixture of isomers;glycerol 1,3-diglycerolate diacrylate; pentaerythritol triacrylate;pentaerythritol tetraacrylate; bisphenol A glycerolate diacrylate;trimethylpropane triacrylate; 3-(acryloyloxy)-2-hydroxypropylmethacrylate; poly(ethylene glycol) dimethacrylate; and ethylene glycoldimethacrylate.
 10. The ultraviolet light or thermally curable resincomposition as defined in claim 8, wherein the azo-initiator is selectedfrom the group consisting of azobisisobutyronitrile;2,2′-azobis(2,4-dimethylvaleronitrile);1,1′-azobis(cyclohexanecarbonitrile);2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile); dimethyl2,2′-azobis(2-methylpropionate); and2,2′-Azobis(N-butyl-2-methylpropionamide.
 11. An ultraviolet lightcurable resin composition, comprising: a predetermined mass ratio of a(meth)acrylate cyclosiloxane monomer and a non-siloxane (meth)acrylatebased monomer ranging from about >0:<100 to about 80:20; an initiatorselected from the group consisting of an acetophenone, a phosphineoxide, a brominated aromatic acrylate, and a dithiocarbamate; a surfaceadditive; and a solvent.
 12. The ultraviolet light curable resincomposition as defined in claim 11, wherein: the (meth)acrylatecyclosiloxane monomer is2,4,6,8-tetramethyl-2,4,6,8-tetrakis[3-acryloyloxypropyl]cyclotetrasiloxane;and the non-siloxane (meth)acrylate based monomer is selected from thegroup consisting of glycerol dimethacrylate, mixture of isomers;glycerol 1,3-diglycerolate diacrylate; pentaerythritol triacrylate;pentaerythritol tetraacrylate; bisphenol A glycerolate diacrylate;trimethylpropane triacrylate; 3-(acryloyloxy)-2-hydroxypropylmethacrylate; poly(ethylene glycol) dimethacrylate; and ethylene glycoldimethacrylate.
 13. The ultraviolet light curable resin composition asdefined in claim 11, wherein: the initiator is the acetophenone; and theacetophenone is selected from the group consisting of2,2-dimethoxy-2-phenylacetophenone and 2-hydroxy-2-methylpriophenone.14. The ultraviolet light curable resin composition as defined in claim11, wherein: the initiator is the phosphine oxide; and the phosphineoxide is selected from the group consisting ofdiphenyl(2,4,6-trimethylbenzoyl)phosphine oxide,phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide,ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate,diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and combinationsthereof.
 15. The ultraviolet light curable resin composition as definedin claim 11, wherein: the initiator is the brominated aromatic acrylate;and the brominated aromatic acrylate is pentabromobenzyl acrylate. 16.The ultraviolet light curable resin composition as defined in claim 11,wherein: the initiator is the dithiocarbamate; and the dithiocarbamateis benzyl diethyldithiocarbamate. 17.-33. (canceled)